Hi all,

I purchased a 2003 JDM Evo 8 (160,000km) a month ago and I have had a lot of issues to sort out with it and I have got to a point where I can't get any further with it. The car arrived 100% stock and virtually nothing has been replaced on it.

Issues:
1. When accelerating with the throttle open anymore than halfway, the car surges. At partial throttle the car holds boost and feels great. WOT feels horrible!
2. Sometimes the car takes a lot longer than usual to start. The car will crank maybe 5 times, I stop cranking it the turn the key and it’s fine.
3. The idle is a little rough (It was worse, but I fixed a few things which I will mention below).
4. When I turn AC on, the idle rises around 400 rpm and I don’t think is supposed to?

Things I have replaced so far:
1. Installed a new genuine IACV (when the car arrived, it was missing a screw which was making the car idle at 2400 rpm). I believe the one on it was a cheap one too so decided to get a genuine one.
2. Installed a new GFB Respons Diverter/BOV. It is vented back into the intake. (The factory one was put on backwards and the valve had melted shut, whoever worked on this car had no idea, I even found a rag sitting on top of the gearbox).
3. New genuine cam position sensor.
4. New TB shaft seals. (Boost leak test revealed these were shot!)
5. New 10psi Turbosmart internal waste gate.
6. New injector seals and filters.
7. New PCV grommet.
8. New rocker cover gaskets.
9. Added some additional ground cables (have heard this can smooth out idle).
10. New ignition switch.
11. New K&N Typhoon intake kit.

Things I have checked:
1. I have tested the MAF plug and all pins are retuning the correct values.
2. I have done multiple boost leak tests. The only thing leaking was the TB shaft seals.
3. Compression test returned 130psi on all cylinders. I did this with the engine at temp with a very cheap tester. Either way, this is low but not overly worrying as all cylinders were within 1 to 2 PSI of each other.
4. Gapped plugs to 0.025” (they were maybe double this or more).
5. Plugs looked fine and are the correct Iridium plugs for a stock evo 8.
6. Cleaned the MAF sensor.
7. Replaced most of the vacuum hoses.
8. I haven’t touched the BISS but I wouldn’t be surprised if it’s been played with at some stage.

The strange:
1. I bought new NGK coil packs, swapped them over and the car kept throwing a misfire code and shutting down?? I put the old coil shaft on the new coils and still did not work, tried the new shafts on the old coils and they worked...



So… Do any Evo gurus on here have any other ideas as to why it is still running poorly?

The only thing I have been able to come up with is that the MAF sensor is dodgy. Dodgy enough to cause my issues but not bad enough to throw a code. The fact that the car threw MAF related codes with new coils is telling me it could be related to that?

I am looking at buying a reconditioned MAF and I have some new NGK Iridium plugs on the way. The only other thing that could be contributing to the issue is the fuel pump. I popped the cover under the seat and it has never been touched. I am also waiting for my Evoscan plug to arrive as that may give me more insight into the issue.

 

maf connection or bad maf.

may try resetting the Ecu also