Suddenly running lean and missing while cruising...
Jun 22, 2011, 11:17 AM
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Suddenly running lean and missing while cruising...
Sorry for the long post but I feel there are several details that need to be covered in order to accurately diagnose my problem.
I have read several threads about similar instances, most were using stock ECU, but none appeared to be exactly like mine.
Short version: Within about 15 minutes of driving, usually under cruising speeds of 60 mph or so, the car will start to miss until its sounds like a subaru and becomes undriveable shortly after. If I changed the plugs, the car will start right back up and run fine for about another 15 minutes and it starts all over again. The plugs barely look used and still remain extremely white. I've even just parked the car and let it sit over night, go for a spin the next day with the same plugs in, like nothing happened and then it starts all over again in about 15 minutes. Any ideas.
Long Version:
About a year and a half ago the car was running lean under WOT. Took it down to the shop and one of the fuel pumps was not turning on. They wired up the pumps to run simultaneously all the time. Slapped it on the dyno and all was good. Car ran decent, but not great for a few months.
The car rarely gets driven as its not my daily driver. I would take it out on the weekends for a quick spin with a 30 min drive tops. Periodically I would feel what appeared to be some kind of miss while cruising on the interstate between 60 and 80. As many have had this issue, they simply tapped the gas a little and it seemed to go away. This happened pretty much every time if I was on the interstate, but not terribly bad. Then one weekend about 15 minutes into my drive on the interstate the car started missing extremely bad. I ended up pulling over because it sounded just like a Subaru engine and was basically undriveable. The AFR’s went from 14.7 and gradually climbed up to 18 – 20 so I pulled over. I had my wife bring my tool box and I had a spare set of plugs and original coils (I was using a COP when the issue occurred). I swapped out the coils and installed the new plugs (BPR8ES gapped to .022). It fired right up and appeared to drive fine but I did not boost it as I was just trying to make it home without issues. Since that day I have had this issue. The plugs appear to be very white as if I’m running lean. The problem will go away if I pull over and change the plugs, but the same thing will happen again after about 15 minutes or so. The last time I drove the car it was busting up if I hit any kind of boost. I basically parked the car for several months due to having a new baby and lack of funds. For about the past 1 year my battery would not hold a charge for long at all. I just keep a trickle charger on it at all times.
Last week I decided to get this bad boy back on the road again. I got a couple sets of plugs and had to make about a 45 minute drive to the performance shop, which I new I would not make the whole way there without issues. I made it half way and of course the same thing occurred. I had to pull over and switch the plugs again and limped the rest of the way to the shop.
I had some other mods done and figured the current issue was just in the tune. I had a 44mm v-band Tial wastegate (previously had 38mm) installed which required some custom fabrication in order to have the wastegate coming off the runners of the manifold. They also checked out my AFR sensor because sometimes it would not come on at all or would stick on 21 at all times (which started after I drove in a really bad rain storm one day). It turns out the sensor was all corroded so they clean it out and hooked it back up. It appeared to read just fine afterwards and turned on every time.
Once we got it on the dyno, at about 6k rpms the car would start cutting up. We pulled out the plugs and realized they were not all the same color. They still looked pretty white but did not all look the same. We did a compression test just to make sure we didn’t have other issues. Everything was up around 175 on all cylinders. We installed the new plugs (Irididum BKR8EIX) and reinstalled the COP I was previously using. The problem improved slightly but not much. After another pull they realized the afr reading at the tail pipe was a 9 and my afr gauge was reading 11. They leaned it out and wallah, it worked like a charm. It laid down 488 on 23-24 lbs of boost. Finished up the dyno tune and took it on the street and interstate. We beat on her pretty hard for about 20 minutes, and had 0 issues, other than my mini battery was completely dead from all the dyno cranks. I got about 20 minutes into my drive and while cruising at about 65 on the interstate, the same dreaded issue I was having before started to occur. Started slightly missing and my afr gauge was reading 15.5 to 16 every time it would miss. It gradually got worse and worse. I limped it the rest of the way home and by that point it sounded like a boxer engine again. I just hooked up the trickle charger and let it sit over night.
The next morning I called the shop to explain the issue. They told me to bring it back and they would look at it. I swapped out the plugs again and she fired right back up. The plugs once again looked mostly white with just a hint of yellow/brown to them. I stopped by the autoparts store and picked up a couple sets of plugs in case they were needed for the trip back. I stayed out of boost the whole way and actually did not have to stop at all on the way back. I felt a couple slight misses but nothing major. I talked with the tuner and he told me the NGK iridium BKR8EIX plugs were probably not the best for an Evo 8, and that I should run the BR8ES or BPR8ES, which I had a set on hand and one extra. I swapped out the plugs and also needed the idle adjusted because the car seemed like it wanted to stall, and with my battery not being in the best condition, I didn’t want to be stranded. He hooked up his laptop and started making adjustments to the idle. He said it appeared that it changed from the night before. I turned the car off and on and all the sudden it was free revving to like 3k rpms and climbing. He said he had no idea what had happened. Turned it off and on again and the same thing happened. I checked the throttle cable and I had forgot to put it back in the little holder clip on top of the valve cover. I did this and then restarted and it appeared to go away. We took it for a 15 minute spin to check everything out. The car ran very well, so good he said he would be interested in seeing on the dyno again because it seemed to hit so much harder. The shop was busy as they were doing dyno runs all day so I didn’t put it back on. I spent the day at the shop and headed back home. Sure enough, about 15 minutes into the drive the same issue showed up again. Pulled off the interstate and did some side road driving and it appeared to go away. Jumped back on the interstate and 5 minutes later it started happening again. It got progressively worse but I just kept going. It got so bad that I had to pull over and switch the plugs within about 5 miles from my house. Got the new plugs in, ran fine for a few minutes and the it started all over. Limped it home and parked it.
I called the shop back on Monday and stated what had occurred. They said I should probably get a new wideband sensor installed and come back so they could better monitor the issue. He said he disabled reading of the AFR by the wideband sensor with it being faulty. He also told me to check for any loose ground wires, try unhooking my aftermarket ignition system and run off the stock one, swap the coils, and see if anything changed. I have also heard of weird issues occurring from a bad battery, so I ordered a battery and Bosch Sensor. I am currently waiting to receive these items and I’ll be headed back to the shop. Anyway, after I got off the phone I started trying to identify anything at all that may be loose or unhooked. I pulled on all the hoses on the intake manifold to see if any were loose. Sure enough, one was definitely loose. The hose on the left side of the intake manifold running to a T, that runs back to the FPR. The hose was not unhooked, but was almost all the way off the nipple and could very easily slide back and forth. I slid it all the way back on and zip tied the hell out of it.
I decided to take her for a spin again to see if the issue was fixed. I left the same plugs in from the day before to that, seemed to be shot by the time I arrived back home a couple days before. The car fired right up but was free revving again. Turned the car off and back on and it was not free revving but idle about 2k rpms. Took it down the road, and still wanted to rev wildly. While in neutral it was wanting to rev up real high again for no reason. Turned it off and on and it was better but not fixed. Drove it around for about 15 minutes and it ran pretty good except for when hitting boost. I hit it hard twice and while at WOT my AFR’s were around 11 then suddenly hit about 12.6 and it started cutting up around 6500, but not bad. I kept driving at cruising speed to see if the missing problem was still there, but it was not occurring. Just as I was about home and thought everything was fixed, the missing issue suddenly started happening again. I drove it home just a few miles away. I pulled the plugs, which looked extremely white, but they were black around the top of the threads. Also, when I went to put the trickle charger back on the battery, I noticed the negative had come completely off the terminal, but was still resting on it. Could this have caused the sudden missing to occur?
The car has been parked since Monday. At this point I don’t know if I have an electrical, fuel, or tune issue. This is driving me nuts! Any ideas what could possibly be happening?
Here are some pics of my plugs. First set is the Iridiums, second is the BR8ES.
Plugs after being on the Dyno and limping home:
Plugs after my last drive after fixing the loose vacuum hose:
Short list of mods:
Built 2.0
6262 .63 Hotside
AEM ECU
Spoolin-up COP
Hyperforce Ignition System
Zeitronix ZT-2 Wideband
Full Blown Dual Fuel Pump Setup w/ Walbros
Precision 1000cc Inj.
I have read several threads about similar instances, most were using stock ECU, but none appeared to be exactly like mine.
Short version: Within about 15 minutes of driving, usually under cruising speeds of 60 mph or so, the car will start to miss until its sounds like a subaru and becomes undriveable shortly after. If I changed the plugs, the car will start right back up and run fine for about another 15 minutes and it starts all over again. The plugs barely look used and still remain extremely white. I've even just parked the car and let it sit over night, go for a spin the next day with the same plugs in, like nothing happened and then it starts all over again in about 15 minutes. Any ideas.
Long Version:
About a year and a half ago the car was running lean under WOT. Took it down to the shop and one of the fuel pumps was not turning on. They wired up the pumps to run simultaneously all the time. Slapped it on the dyno and all was good. Car ran decent, but not great for a few months.
The car rarely gets driven as its not my daily driver. I would take it out on the weekends for a quick spin with a 30 min drive tops. Periodically I would feel what appeared to be some kind of miss while cruising on the interstate between 60 and 80. As many have had this issue, they simply tapped the gas a little and it seemed to go away. This happened pretty much every time if I was on the interstate, but not terribly bad. Then one weekend about 15 minutes into my drive on the interstate the car started missing extremely bad. I ended up pulling over because it sounded just like a Subaru engine and was basically undriveable. The AFR’s went from 14.7 and gradually climbed up to 18 – 20 so I pulled over. I had my wife bring my tool box and I had a spare set of plugs and original coils (I was using a COP when the issue occurred). I swapped out the coils and installed the new plugs (BPR8ES gapped to .022). It fired right up and appeared to drive fine but I did not boost it as I was just trying to make it home without issues. Since that day I have had this issue. The plugs appear to be very white as if I’m running lean. The problem will go away if I pull over and change the plugs, but the same thing will happen again after about 15 minutes or so. The last time I drove the car it was busting up if I hit any kind of boost. I basically parked the car for several months due to having a new baby and lack of funds. For about the past 1 year my battery would not hold a charge for long at all. I just keep a trickle charger on it at all times.
Last week I decided to get this bad boy back on the road again. I got a couple sets of plugs and had to make about a 45 minute drive to the performance shop, which I new I would not make the whole way there without issues. I made it half way and of course the same thing occurred. I had to pull over and switch the plugs again and limped the rest of the way to the shop.
I had some other mods done and figured the current issue was just in the tune. I had a 44mm v-band Tial wastegate (previously had 38mm) installed which required some custom fabrication in order to have the wastegate coming off the runners of the manifold. They also checked out my AFR sensor because sometimes it would not come on at all or would stick on 21 at all times (which started after I drove in a really bad rain storm one day). It turns out the sensor was all corroded so they clean it out and hooked it back up. It appeared to read just fine afterwards and turned on every time.
Once we got it on the dyno, at about 6k rpms the car would start cutting up. We pulled out the plugs and realized they were not all the same color. They still looked pretty white but did not all look the same. We did a compression test just to make sure we didn’t have other issues. Everything was up around 175 on all cylinders. We installed the new plugs (Irididum BKR8EIX) and reinstalled the COP I was previously using. The problem improved slightly but not much. After another pull they realized the afr reading at the tail pipe was a 9 and my afr gauge was reading 11. They leaned it out and wallah, it worked like a charm. It laid down 488 on 23-24 lbs of boost. Finished up the dyno tune and took it on the street and interstate. We beat on her pretty hard for about 20 minutes, and had 0 issues, other than my mini battery was completely dead from all the dyno cranks. I got about 20 minutes into my drive and while cruising at about 65 on the interstate, the same dreaded issue I was having before started to occur. Started slightly missing and my afr gauge was reading 15.5 to 16 every time it would miss. It gradually got worse and worse. I limped it the rest of the way home and by that point it sounded like a boxer engine again. I just hooked up the trickle charger and let it sit over night.
The next morning I called the shop to explain the issue. They told me to bring it back and they would look at it. I swapped out the plugs again and she fired right back up. The plugs once again looked mostly white with just a hint of yellow/brown to them. I stopped by the autoparts store and picked up a couple sets of plugs in case they were needed for the trip back. I stayed out of boost the whole way and actually did not have to stop at all on the way back. I felt a couple slight misses but nothing major. I talked with the tuner and he told me the NGK iridium BKR8EIX plugs were probably not the best for an Evo 8, and that I should run the BR8ES or BPR8ES, which I had a set on hand and one extra. I swapped out the plugs and also needed the idle adjusted because the car seemed like it wanted to stall, and with my battery not being in the best condition, I didn’t want to be stranded. He hooked up his laptop and started making adjustments to the idle. He said it appeared that it changed from the night before. I turned the car off and on and all the sudden it was free revving to like 3k rpms and climbing. He said he had no idea what had happened. Turned it off and on again and the same thing happened. I checked the throttle cable and I had forgot to put it back in the little holder clip on top of the valve cover. I did this and then restarted and it appeared to go away. We took it for a 15 minute spin to check everything out. The car ran very well, so good he said he would be interested in seeing on the dyno again because it seemed to hit so much harder. The shop was busy as they were doing dyno runs all day so I didn’t put it back on. I spent the day at the shop and headed back home. Sure enough, about 15 minutes into the drive the same issue showed up again. Pulled off the interstate and did some side road driving and it appeared to go away. Jumped back on the interstate and 5 minutes later it started happening again. It got progressively worse but I just kept going. It got so bad that I had to pull over and switch the plugs within about 5 miles from my house. Got the new plugs in, ran fine for a few minutes and the it started all over. Limped it home and parked it.
I called the shop back on Monday and stated what had occurred. They said I should probably get a new wideband sensor installed and come back so they could better monitor the issue. He said he disabled reading of the AFR by the wideband sensor with it being faulty. He also told me to check for any loose ground wires, try unhooking my aftermarket ignition system and run off the stock one, swap the coils, and see if anything changed. I have also heard of weird issues occurring from a bad battery, so I ordered a battery and Bosch Sensor. I am currently waiting to receive these items and I’ll be headed back to the shop. Anyway, after I got off the phone I started trying to identify anything at all that may be loose or unhooked. I pulled on all the hoses on the intake manifold to see if any were loose. Sure enough, one was definitely loose. The hose on the left side of the intake manifold running to a T, that runs back to the FPR. The hose was not unhooked, but was almost all the way off the nipple and could very easily slide back and forth. I slid it all the way back on and zip tied the hell out of it.
I decided to take her for a spin again to see if the issue was fixed. I left the same plugs in from the day before to that, seemed to be shot by the time I arrived back home a couple days before. The car fired right up but was free revving again. Turned the car off and back on and it was not free revving but idle about 2k rpms. Took it down the road, and still wanted to rev wildly. While in neutral it was wanting to rev up real high again for no reason. Turned it off and on and it was better but not fixed. Drove it around for about 15 minutes and it ran pretty good except for when hitting boost. I hit it hard twice and while at WOT my AFR’s were around 11 then suddenly hit about 12.6 and it started cutting up around 6500, but not bad. I kept driving at cruising speed to see if the missing problem was still there, but it was not occurring. Just as I was about home and thought everything was fixed, the missing issue suddenly started happening again. I drove it home just a few miles away. I pulled the plugs, which looked extremely white, but they were black around the top of the threads. Also, when I went to put the trickle charger back on the battery, I noticed the negative had come completely off the terminal, but was still resting on it. Could this have caused the sudden missing to occur?
The car has been parked since Monday. At this point I don’t know if I have an electrical, fuel, or tune issue. This is driving me nuts! Any ideas what could possibly be happening?
Here are some pics of my plugs. First set is the Iridiums, second is the BR8ES.
Plugs after being on the Dyno and limping home:
Plugs after my last drive after fixing the loose vacuum hose:
Short list of mods:
Built 2.0
6262 .63 Hotside
AEM ECU
Spoolin-up COP
Hyperforce Ignition System
Zeitronix ZT-2 Wideband
Full Blown Dual Fuel Pump Setup w/ Walbros
Precision 1000cc Inj.
Last edited by Eartears; Jun 22, 2011 at 06:32 PM.
Jun 22, 2011, 06:43 PM
#3
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Take off the COP system and put back the factory coils for one. Then go check the pumps to see if they are coming loose out of the holster. You should NOT be running both pumps on at the same time at idle, you are flooding the fuel rail. Psi will jump from 43.5 to 60psi with 2 walbros on at idle. There is boost switch required for a reason.
Jun 22, 2011, 06:59 PM
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I'm pretty sure you know this About the full blown hanger ,but make sure you have more than 1/4 tank of gas any less shell starve. Also. Can you tell us how much voltage you have on the battery while cruising. ?
Jun 23, 2011, 03:56 AM
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Take off the COP system and put back the factory coils for one. Then go check the pumps to see if they are coming loose out of the holster. You should NOT be running both pumps on at the same time at idle, you are flooding the fuel rail. Psi will jump from 43.5 to 60psi with 2 walbros on at idle. There is boost switch required for a reason.
I was unaware of the side effects of running both pumps simultaneously. I will have this switched over and see what happens.
Jun 23, 2011, 04:00 AM
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Voltage is probably not much at all as its just a mini battery and it barely holds a charge anymore. I probably only get like 5 cranks out of it and its done unless I make a long drive or keep on the trickle charger. I got a brand new one in last night. Waiting on my wideband sensor and I'll be headed back to the shop.
Jun 23, 2011, 04:17 AM
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It shouldn't matter. Your alternator should be pumping and regulating around 14v cruising. Get a full tank of gas and let me know your voltage at cruise. Then you can troubleshoot a little better. Also. With your aem you can trigger your 2nd pump to come on when ever you want. Let me know how she does so we can get it fix.
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Jun 23, 2011, 04:18 AM
#8
Hooking up a fuel pressure gauge and watching what it does when the problem occurs will eliminate a lot of troubleshooting , or will find the problem immediatly!!
Does AEM use the front 02 ? If so When was the last time you replaced your front 02 sensor?
Does AEM use the front 02 ? If so When was the last time you replaced your front 02 sensor?
Jun 23, 2011, 04:38 AM
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I have a Aeromotive FPR and gage installed under the hood, so it a little hard to monitor unless I get it back on the dyno. I periodically check it while idling in my driveway and its usually right around 45 psi.
Last edited by Eartears; Jun 23, 2011 at 06:26 AM.
Jun 23, 2011, 06:36 AM
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Im not sure about AEM using the front O2 sensor. I believe it must because my wideband sensor isn't working correctly, so my tuner disabled reading off this sensor and has AEM reading off a different one.
Jun 23, 2011, 06:46 AM
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He probably turned off feed back if it was bad and just tuned around it. And yes. You don't use the narrow band o2 with aem just the wideband.
Jun 23, 2011, 12:03 PM
#13
It sounds like you have a few things to check out keep us updated on what you find out regarding the Walbro hookups and FP.
Jun 23, 2011, 12:54 PM
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I might just have to do this. I will keep everyone posted. I've found several threads about this issue but most guys usually just disappear and never say how they fixed it. I'll post back.
