Girl friend just bought a 2003 Lancer Evo 8. It has an AEM Fuel Rail, Walbro 255 fuel pump, HKS 272 Duration Camshafts, a turbocharger off an Evo 9, and it's pushing 20 psi of boost. Now for the issue, it seems like when I do any pulls, from 4500 rpm - 7000 rpm it tends to get a little burpy and backfire as it RPM's. The guy we bought it from was with us and said "It's sat for 2 weeks without being driven and it's never done that before.. I don't know why it's doing that." He also said he's never touched the spark plugs and that it was running Bosch Platinums.. I took the cover off and pulled one of the plugs tonight to see that it was actually a NGK R-Type Spark Plug. What I need to know, is based on the given information, what plug should I run in this car and should it be gapped to any extent? I'm very sorry for making a new post, I'm just very tired right now and need an answer soon. If someone could help me out so that I could have an answer when I go to work on it tomorrow afternoon, I would be eternally grateful to them. Thanks in advance!

 

Did he mention anything about a tune? My car did the same thing at 4500, its called a fuel cut. If you upgrade any parts without a tune its basicly confused. All I can say is get a tune

 

Its probably the plugs man. If your on stock coils gap them down to .18 or .20. You can get the part number for the evo 8 spark plugs fairly easy. I have a 9 so I font know but it sounds like your ignition is busting up at high rpms.

 

Search evo 8 or 9 fuel cut

 

To determine if it's fuel cut you really need to know what injectors turbo and power your pushing. He's obviously running some kind of tune if he's running the walbro with no issues. Do you have a wideband to check your a/f? My suggestion do the plugs first. I wouldn't think 20 psi on pump gas would cause fuel cut but I could be wrong

 

Copper NGK's ----- BPR7ES gap to .026

 

Another note, fuel cut wouldnt allow you to "burp" up to 7500 rpm. You'd simply stop in the rev range. In the state of your car build with cams, turbo, fuel pump... You probably have a tune already, but you shouldve asked that question when you bought it lol... But sounds like youre getting break up, plugs are usually the culprit. Easy to check anyways.

Also, dont use platinums for Evo 8's. You wont get good results, search around EVOm. Just throw in the good ole coppers and gap them to what I said previously, .026.

 

Thanks everyone, I really appreciate it. He did have somewhat of a tune on it. It's running the factory ECU and 1000cc Injectors. I asked him what he used to tune it and he said it was an AEM program on his laptop. God knows what interface it was. I'll do the plugs and see if that helps it out a bit. Also has no wideband, he mentioned that as well. Once again thanks very much, I would not get off easy with a post like this on SupraForums.

 

No wideband? That's not good. You should really get your car to a tuner.. And see if he can pull the current ROM and read some maps.. To check if your even safe. You should really be monitoring AFR with your current setup. Also when you say AEM program, I'm pretty sure you would have an AEM standalone EMS.. You should find that out

 

agreed. Sounds like the previous owner doesn't have a clue.

 

Do you have licp or any icp beacuse when I first started modding my 9 I had injen piping kit with intake and tbe and I used cobb ap until I get my real tune and it ran pretty good then I sold the piping kit to get ets and only had tbe and ets intake it started to do that a little but once I got my new piping it stopped that. Just my input cuz it was doing almost the same to me but I also got a tune soon after the new set up.

 

Sounds to me like a boost leak

 

I got the NGK Spark Plugs that one of the above mentioned, gapped them to .026, and it runs beautifully now. No problems getting to RPM, no "burps", misses, or backfiring. I'm gonna look into the EMS a bit more later on. Unfortunately, she's gonna be out of money soon as she just had to fix her Dodge Stealth. Once again, I appreciate all the help so much. I'll let her know she should look into getting a wideband A/F and check into getting a tuner to look at it as well. But for now, the car runs fantastic. Thanks everyone.

 

ITs not fuel cut, u need new plugs, copper plugs every 3to 5 k.....they foul quick, i used the bpr8es on mine before, there one step colder, personally id try iridium stock heat range, then down the road with higher boost then one step colders would be more What u need....good luck. Make sure to check gap first before installing new plugs.

 

I told you it was the sparkplugs you need gap them to .20 if your on stock coils.