I've got a catback, adjustable cam gears on factory cams,a K&N filter, and a reflash for these mods. I have the bleeder tube installed by-passing the boost control solenoid per vishnu directions.

The car will pull fine on the dyno and hold a solid 20 psi but, on the street when rolling in any gear below fourth if I hit full throttle the boost will go up to 21 psi. Then the car will start to stutter and loose power and boost will drop to @ 19psi. It will also puff a small cloud off unburnt fuel out of the exhaust pipe when this happens.

I first thought this was just due to the cold weather during winter but, it did this the other day when it was 80 degrees out too. Any suggestions? Is this something I have to live with? I've e-mailed Vishnu and they have not replied so I'm looking for some help here.

 

like you said, sounds like you are running to much boost and your car is pulling timing, dumping fuel. Have you changed the plugs in it before? If you're still running on the stock plugs with alot of miles on them you may want to try the colder ngk's. That may help, if not you could send the ECU back and get the boost turned down some.

 

I don't think you are overboosting. Change out the plugs like EH said above. You can save a lot of cash going with the NGK BR7es (stock heat range) or the BR8es (one step colder). Gap 'em at .026 and reset your ecu by disconnecting your negative battery for a few minutes. Make sure that you have good gas.

Do you have ANY other mods that you didn't mention? BOV, plug wires, etc? Did you over-oil your K&N filter?

 

The plugs are Denso iridium's stock heat index. Gapped at .030 with 10,000 miles on them. The gas is from the same place I always get gas and a guy I work gets gas there as well in his 550 whp supercharged capri. So I don't think it's the gas.

I'll check the plugs again tonight but, I don't think it's the problem.

 

Do the Denso's have the solid tips where the boot connects? I noticed when I had some NGK iridiums they had the screw on tips without the solid tips. This caused the electricty to arc from the boot to the plug. It had alot of carbon build up around the tip and caused the car to bog like that. You might want to try to regap yours to .26-.28 and see if that helps.

 

from what i remember denso's also have the screw on tip

 

Maybe I'm not doing a good job of describing it. The car will run fin under most conditions including high boost levels. It will only happen at wide open throttle and after it has been over 20psi for a second or two. Once boost goes back below 20psi it pulls strongly again. When it is "stuttering" it sounds like the traction control working on an F1 car, a series of rapid pops then clearing up.

The Densos do have the screw on tip.

Any one from Vishnu care to reply here?

 

Sounds like what I used to experience with my XFlash (Stage 0+). I think it is just the ECU pulling timing, not overboost (I have experience with overboost too-not XFlash related though).

Does this happen to you while in 4th or 5th gear during rollon acceleration from 50mph-70/80mph? That's when I would get it, whenever I stomped on it while on a roll in a high gear.

I don't think I ever got a clear explaination for the cause of this either...maybe it's just a phenomenon we have to be conscious of and try to avoid it. Downshift instead of just hitting the gas while crusing.

I'd be interested in anyone else's thoughts too...good luck Hotrod.

 

That sounds alot like P0300 stumbling...

 

I had the P0300 in my other Evo and it was way different than this. In my other Evo it would start to pull strong and then you would get to the misfire range of rpm and it would just about put you through the windshield. This not nearly that drastic and hasn't thrown a CEL yet.

I pulled the plugs. They were still @ .030 so gapped them down to .026. It does seem to run better but, I can't say that fixed it for sure. I didn't get enough open road to really get on it and it was pretty warm yesterday.

I did notice that number one cylinder is running a good bit leaner than the rest. While the other plugs had an instant cocoa powder color to them, #1 was white. It was also gapped the farthest so maybe its been the cause of the misfire?

 

After a couple of pretty good WOT runs up and down some on & off ramps I think it's fixed. I thought .030 was a pretty tight gap, I guess not for forced induction.

Thanks for the help.

 

Glad to hear that you think it's fixed. Quick question though: Is that plastic airbox elbow secured to the radiator support with those two annoying fasteners or is it just sitting there unsecured?

Shiv

 

It should be fastened. I don't recall ever unfastening it. Are you talking about something securing the plastic pipe to the turbo from the MAF?

 

No, the Air intake scoop that connects to the stock airbox. There are two plastic screws that hold the scoop to the frame of the car. If one of the screws or both are missing, the scoop will sometimes colapse as air is being pulled into the airbox.

 

One is missing on the inlet to the air box. I've been meaning to get a replacement. I'm actually heading to the dealership tonight for brake caliper issues.