Mods that matter- 2.3, S2 cams, FP black, E85, 1450 FIC's, JDM/X 3 bar map speed density


I just recently replaced the plugs as my 91 tune was all jacked and fouled them out (was BR8ES) replaced with BR7ES gapped to .026. I randomly started getting a relatively poor idle, the cams are lopey, but this was like a miss at idle. AFR's were starting to get leaner and leaner, to the point that it now idles in the 17's and will randomly jump into the 14's then peg the guage lean, and it continually bounces around like that when warm, cold starts hold pretty steady in the 14-15's and it seems to idle fine then with -12in/hg, it begins to miss around 20 seconds into idling, however, when idling good the car will peg lean if you touch the gas. I cannot drive it at all until it's idled for 30 seconds+.


Last week I noticed cruise afr's beginning to go leaner as well. It cruises in the 16's-17's and I noticed if I got into the throttle a bit it would start to richen back into the 14's. Almost as soon as I hit 0in/hg the car goes dead lean (17's), looses all power. I've only gotten up to 5lbs, I would always let out seeing it as lean as it was. Fuel pressure at idle sits around 41lbs, and it will increase to around 50 if I put my foot down (out of boost), so I'd assume my fuel pump isn't failing which was my initial thought. We bench tested my map sensor at work and it was stuck at 2.2v, however, I'm not sure I trusted the test 100%. Regardless we ordered a new map and I put it in tonight, idle is still lean and rough. I noticed last week while logging I couldn't get any fuel trims to develop, the o2 seems to be cycling, and the car was up to about 170F so it should've began developing trims, but it never did.


I have a log attached of some idle and cruise with minor spurts of boost. Maybe someone can catch something I've missed in the logs? Note that my wideband isn't currently being logged, however, AFR's are constantly in the 16-17's with random spurts of 13-14's during cruise (1 second spurts at most). It seemed like my duty cycle wasn't really increasing at all with throttle, but maybe I'm just looking into it too much.


On a side note, the tach only works when it's jumpered to pin 89 (CKP sensor), I'd assume this has no correlation to my issue as it was jumpered by the PO and ran fine before, but I can't seem to find where the tach signal is derived from. I'd assume the CKP as jumpering makes the tach work perfect.


Let me know what you see!

https://www.dropbox.com/s/lbt5g732sj...4_06.28.13.csv
https://www.dropbox.com/s/w9u4ua7jk0...4_07.24.37.csv

 

Quick update- I switched between my 91 and E85 map to see if that changed anything and no-go. I also changed the "minimum temp for closed loop" value from 0C to 200C to try and eliminate a closed loop issue and same thing as before. I noticed that if I barely put my foot in (wasn't logging) around 5-10% throttle the car goes extremely lean and stutters like it's about to die. If I put my foot into it a little more the car will pull through the stutter and rev up nicely and continue to rev as long as I don't pull my foot back completely off the throttle. Reviewing my logs shows the TPS seems to be working fine, although it may not be able to catch a dead spot in the sensor.

The weird part is on first start up hot/cold, the car will run great for about 5- maybe 10 seconds tops. Then as the idle comes back down it begins to stutter and shake. I did notice also today when I turned the key to "on" fuel pressure only went to 20psi. It jumps right to 43psi when i crank it though. The car starts surprisingly fast for a larger injector, E85 car, so I have a hard time condemning a fuel pump .Anyone have any other ideas?

 

What about checking your temp sensor input? - either fuel temp or IAT depending on your SD set up.

 

As of right now it's wired to the fuel temp, but Im pretty sure it isn't working. Whoever wired it put a gm IAT in the uicp and wired it but apparently it's not hooked up at the ecu anymore. When logging I get a steady 77F IAT, so I'd assume it isn't working properly although temps have been in the 70-80s.

It's been like that since I bought it though so I have a feeling the IAT isn't the issue.

 

Another update- working on the car right now. I back probed the map to see how it was working/if it was working. I've got a 5V reference, the signal wire while off (0in/hg) is at 1.43v which seems normal. I plugged my boost leak tester in and watched and voltage increased just like it should. I'm going to assume the MAP is fine. While logging it on evoscan it sits around -6in/hg at idle (I'm assuming this is relative? not absolute? maybe I have them mixed up) as I pull about -12in/hg, and it will increase on evoscan with throttle.

TPS- 13.33% on evoscan, increases to just shy of 99.8% at WOT.

Front o2 (since I'm running the AEM wideband off it's own bung rather than narrowband simulation)- Cycles between .2-.6V at idle and seems to follow my AEM gauge linearly. If I give it throttle and get the AEM to richen into the 13:1 the AEM will increase into the .6V range. So with that I'm going to assume both my wideband is reading correctly, and my o2 is working properly.

This leads me to an obviously lean conclusion- but why? I have 43ish psi at idle and it will increase to 50psi if I free rev. Normally I'd assume since pressure is good everything up to the injectors is OK, but I do know you can have a lack of flow while still having pressure. I'll be pulling the fuel pump out next to ensure the sock isn't clogging just to be 100% and I'll probably pull the fuel filter for the same. The last thing it could be other than a possible injector driver issue is the injectors themselves correct? I have both a spare evo 8 ecu, as well as stock evo 8 injectors that as a last resort will be put in for verification, but can anyone else think of anything that would cause this?

Side note which is probably unrelated- I noticed the PO jumpered pin 58 to pin 89 (tach to CKP signal). I disconnected the jumper and found what I assumed would happen- tach quit working. Since it was jumped to the CKP I'm going to assume that's where the RPM signal for the tach is derived? I can't get any verification on this. It's jumpered right at the ECU connector itself, so that eliminates anything forward of the ECU being an issue, and if the signal is derived from the CKP and the CKP signal wire is working correctly am I correct in assuming the driver in the ECU has gone bad? Bringing it back full circle if the tach driver is bad, this could potentially lead to other ECU related failures (injector drivers)? Just trying to use process of elimination. Again let me know what you think guys! Sorry for the long winded response, just making sure all the information is out there since you cant have your hands personally on the car.

 

Update again: Checked timing to verify it hadn't jumped. Timing is dead on.

Pulled the spark plugs- All the gaps were still good at .026". Cyl1 was noticeably lean, very white electrode. Cyl 2 was lean but not as white as cyl 1. Cyl 3 even less white and cyl 4 was about what a normal plug would look like maybe slightly lean. I looked down into each cylinder and cyl 4 has coolant in it. I started with a leak down test- it tested nearly perfect, weird. Compression test gets kind of funny. When we first bought the car we used my compression tester and got 150 across the board HOT. Today we used a buddies as mine is loaned out to a friend. Cyl 4- 210psi, Cyl 3-190, Cyl 2- 190, Cyl 1- 190 COLD. I figured the increase in cyl 4 was from coolant, so I blew the cylinder out the best I could and retested- 200psi.

So why do I have coolant in the cylinder? No FIAV, so no way for coolant to run through the throttle body. Intercooler pipes were clean so I don't believe it's coming from the turbo. It couldn't have been doing it for very long as the cylinder still has a bit of carbon build up on the piston and isn't super clean like it should be when it burns off water/coolant. I know the next step would be to pull the head, but it's hard to justify ripping it apart when all the tests came back normal

On a side note I pulled the pump last night for ****s and giggles. Full factory pump, never had been taken out before. I find it odd considering it's a 2.3 and FP black, but I never had issues with it going lean when I first had it. For having 130k on the body the tank was ridiculously clean. Rubber doesn't last long in the AZ heat, but the lines in the tank felt brand spanking new.

 

Update again-

Pulled the head as there was coolant in cylinder 4 (still had good compression and oddly had zero leak down). So we pressure tested the head and all was good. Resurface and reinstalled the head which is where I'm at now- now it's missing on 1/4.

The car is hard to start, and when it does start it's a noticeable miss. Removing injector plugs on cyl 1/4 yields no change in idle, same with pulling the plug wires. I have 40psi of fuel pressure at start up, I have spark and have swapped coils to verify it isn't a coil issue. If I spray brake clean down the bov vacuum port there is no change in idle. Compression is 180 across the board cold.

I've also tried swapping the cam sensor reluctor wheel around to make sure I didn't put it on 180* and either direction yields the same results. If I put a screw driver up on the 1/4 injectors I can't hear them clicking, however, I have 12v on the positive side of each. My wideband now is pegged dead lean --- and reads nothing, so im not sure if the sensor was damaged at all yet as it was reading earlier when I first started testing. Logging in evoscan my front o2 stays at 0 with it running and crank signal stays at zero as well. I did notice (as previously posted) that my tach wire at the ECU was jumpered to my crank signal wire and disconnecting the jumper kills the tach. My tach is working with the jumper connected though.

Is there any sensor that directly correlates cylinder 1/4 injectors? Obviously the coil fires on both cylinders, but I strongly believe fuel is the issue and not spark.

 

check resistance for injector pack and bell out (continuity) the wiring from ecu to connectors for 1 and 4 injectors and coil pack

 

Forgot to mention last night that I did test the resistor pack and the ground side wires test good to the ecu from the injector connector

 

injector resistances ok ?? did you try different crank and cam sensor

 

Injectors all ohmed within .1

I'd rather not throw parts at it. If I could drive it I'd take it to my shop and put a scan tool on it with the ocilliscope but I can't currently.

 

Mate, i've got the exact same issue at the moment. I'm on Stock turbo, FIC 1450, E85, BR8ES, Spoolin up COP. Tune was all good and fine for a month and out of the blue its leaning out. I've checked injectors, plugs, coilpack

Once it hits 0inhg it would lean out and i'd get CEL light knocks. >3 and >6 at times on partial throttle up to about 5psi at 50% throttle. (like you, once I go more, it'd richen up but too scared to even boost it now)

How is your vacuum on idle? mine used to be on -16inhg, now its hovering around -10/-12inhg so im assuming I have a vacuum leak..

I've made a boost leak tester but still trying to find a compressor and going to do it over the weekend. Keen to hear your results too mate.

I'm thinking it could be my fuel filter/cradle too. I'm yet to pull that and check, but I didn't change it when I installed my Walbro..

 

Are you on SD of maf? If you're SD that sounds like my original problem which was a bad MAP sensor.

My idle sits around -12in/hg which is where it always has. I believe the tuner that setup the car tried to get the car to lope as the previous owner really liked the sound. If I adjusted the timing or Afr at idle I could bring vacuum back to -15in/hg without fully dialing it in. I've boost leak/vac tested the car multiple times before and it holds very well so that's my only understanding as to why my vacuum is so low

 

I'm on MAF.

Ahh. Fair enough. I'm yet to do my boost/vac test yet and checking my fuel cradle so i'm hoping its one of them. I thought it was injector gunk etc so I'm running 98 now (i'm from Australia) but no dice.. still happening

 

I pulled my pump hoping for the same and I was surprised to find that
1-I was the first person to pull the pump, it was still on the original 8 pump and
2- it was spotless. Like brand new spotless. Everyone says e85 breaks down factory lines and destroys them. My factory lines felt brand new and the tank was the cleanest tank ive ever seen