I was checking out my friends evo that is having issues.. When driving the car in 4th gear, if you go WOT the evo will start boosting, get to about 4K and starts surging and backfiring. (Suspected KNOCK)


Bad EVO @4K:
ECULoad 159.38
InjPulseWidth 25.86
AirFlow 1603.95
KnockSum 12
Timing Advance 3
Load 359

My Evo @ 4k:
ECULoad 159.38
InjPulseWidth 13.82
AirFlow 981.24
KnockSum 0
Timing Advance 6
Load 215

So what confuses me about the above is that the airflow is reading double what a working evo is reading. I notice it is Knocking, but i think that might be more a symptom then the problem.


Any thoughts or insight would be appreciated.. I'll probably be swaping our MAF sensors this weekend to see if that is the issue.


Thanks,
-Zach

 

bump.

 

I'm not a MAF expert, but I have encountered similar problems when my plugs were either bad, or gapped too far.

When my MAF went bad, it was quite obvious. The honey comb was completely sucked out. You can take a look at the MAF in question to determine if it looks damanged. Im not certain however if the MAF internals beging to malfunction with time...

Good Luck...

 

Is this a 2.3?

 

denolloyd: When you had your problem did you datalog it? did you see the Airflow going that high?

2.3? I am guessing you are asking about the engine size? It is a stock 2L . Stock turbo as well.. Car does have full exhaust though.

I have inspected the honeycomb already and it appears fine. Just that the reading seem WAY off.

Has anyone else that has datalogged their evo seen these numbers on a stock turboed 2L?




Thanks,
-Zach

 

When i switched to speed denstiy i never had surging problems again, unless of course im in 6th gear at like 2k rpms and i flat foot it. Even with how good stock ecu tuning has become the MAF still causes issues, and a major one is surging.
It is kind of wierd though that the airflow reading is that high.

 

Surging may be to lax of a way to describe this as well.. it is actually close to a rev limiter. It will climb if you keep on it. but that would seem like a bad idea haha..

 

Knock sum may be doo to missfire, not the other way around. Change the plugs and if that does not correct it, swap in your maf and see how it goes. Does the problem car have an after market intake?

Also if he has larger injectors and has been tuned for them , the logged load calc will be off unless you put the proper scale factors in the logger.

In addition, piggy backs that alter maf signal will result in higher maf reading if fuel is being added in that region.

 

Thanks for the responses so for... A few things to note about his car.


Evo8
Stock Engine,turbo,ems (Has flash though)
Panel Filter replacement
Turbo Back exhaust.


He does not have an I/C kit/piping, aftermarket Intake, or piggyback.


I can see where the knock could come from lots of things, that is the other thing that worries me. But i don't see how that would raise the airflow which makes me think it might be more of a symptom then anything.

He should probably change his plugs out anyway as he is at 30K miles and i am not sure if it has been done yet.


Thanks,
-Zach

 

yes check the plugs I had a similar problem didnt log it but from what you are describing sounds like it. Its easy just change the plugs and if it goes away your set, only takes 5 min anyway. Anytime it was under load it would start to surge but it was obvious scared the **** out of me at first but once I figured it out it was all better