Hey everyone.New member from Belgium here and since a few weeks the proud owner of a 08 Evo IX.
Ok here's the problem.About 2 weeks ago my CEL came on.I drove home,opened the hood and checked if I could see something that wasn't right but couldn't find anything apart from the hose that connects the throttle body to the IC piping being taped.
I dropped the hood to close it and noticed the car almost stalled.It does this every time I drop the hood which I find really strange.
Next day I removed the tape to see if the hose was damaged.I could see a small cut in it but it doesn't seem to go through so I left the tape off.
After reading the engine codes the car threw a P0170 Fuel Trim Malfunction (Bank 1) code.
The car also seems to be running rich(about 150 miles on a full tank,200 if I drive like a granny) and seems to be lower on power than it should be.I expected more from a car that has nearly 300hp.
From what I have read the 2 most likely causes are a faulty MAF(anyway I can check this?) and a boost leak.But why does it nearly stall then when dropping the hood?Could this be related to the P0170 code?
I really need your help.I have erased the CEL 5 times already but it keeps coming back and it's driving me crazy.

 

Is your hood hitting the intake pipe? Mine was hitting just a little and every time I shut the hood it hit the intake pipe and jogged the maf. Moved my intake and it never happened again.

 

I already tried to see if the hood hits something but is doesn't look like it.It also nearly stalls when I don't drop the hood hard enough to close it.I'll check the pipe again this afternoon just to be sure.

 

Common for these cars.... Like funevo said, just move the intake a bit.... I've heard of cars stalling out at the track when next to a big v8 doing a burn out haha

Nothing to worry about!

Cheers!

 

Okay thanks will move it a bit and see if it solves the problem.
Any ideas on the P0170?Fuel consumption is driving me mad.

 

hmm thats interesting, My car would drink gas due to the O2 sensor but u dont have that code. Im curious as to wat your issue is

 

O2 sensor was also listed between the possible causes but from what I have read it's more likely MAF or boost leak.I just need to be sure what causes it before I start replacing parts.

 

It is the knock sensor detecting the hood slam!! Same reason your car will stall/bogg down if you are next to a Harley Davidson, or other loud bike at the traffic light. This is TOTALLY NORMAL. Your knock sensor picked up the noise and the ECU "Thinks" its your motor "knocking". dont worry it is FINE. (At least the hood/stalling is from slamming the hood). Running rich, boost leak. If you have a "Cone" airfilter, the oil on it can contaminate the tungsten wire in the MAF and cause some "misreads" too. get the special MAF wire cleaning spray to clean the wire, done. your welcome. lol

 

*side note* if you run around the idling car in your Belgian wooden shoes, the knock sensor may pick that up too?? LOL. jk, I rarely get to use Belgian wooden shoe jokes anymore.

 

No cone airfilter.Can I use brake cleaner to clean the wire?

 

DON'T use Brake cleaner. Use the MAF specific spray. Other stuff may ruin the wire in there. I say you have a boost leak somewhere! Check ALL connections period. There are nipples on the throttle body, make sure those small vaccuum lines are attached too. It is a simple fix, but I put my money its in the hoses.

 

+1 on boost leak. Almost 100% for sure.

 

i also noticed you say you have an 08 Evo IX....did they make an Evo IXs in 08??

 

if you have an open air filter/cone... slamming the hood can cause enough air turbulence in the maf to temporarily skew readings and cause a quick stumble... but it should catch itself right away. Its normal.... my car used to do this every once in a while and i had NO CODES or issues w/ it. And when i closed the hood softly, nothing happened. Only when i dropped it down.

 

thinkin the same thing lol