Problems with boosting and stuttering

[Mad Dog Bodine]

Hey everyone,

I have had this problem come up recently, where my car will not make any boost past 6psi without stuttering and hesitating. I step on it in any gear, and once positive boost starts to hit, after 5-6psi, the car stutters, you can hear it from the exhaust, and it kinda feels like its hesitating. It never goes away in the higher RPM, it just continuously stutters. I can't really get over 4500RPM cause I don't want to keep my car stuttering too long. Everything else about the car is fine, idle, normal driving, light acceleration. Just when I pedal to the metal it, she won't boost.

Here are a couple of the things I have already checked....I have checked my MBC, to see if that was the culprit, doesn't appear to be, cause I have pulled the line off the back of the y-pipe and it still did the same thing. Even though I have a crappy RFL, it doesn't appear to be leaking. I have tried disconnecting the ECS computer....nothing.

Things I haven't done, pressure tested (need to get an adapter), I haven't checked the Caps on the ECU, I will be in the next day. I haven't changed my fuel filter(cause its probably due). My plug wires are about 7 yrs old, plugs were installed at the beginning of last summer gapped to .32. I don't believe its spark blow out.....but I guess I could be wrong. I have logged a bit with my Hybrid HHH logger, but when I export into a CSV file, all I get is a mess of data that isn't well layed out. Anyone know how to organize it properly so I can post it? The file right now is just a mess....lol so I hope I don't have to manually organize it.....

Anyways....thanks for your time.

MDB

[BlackStealth]

My car has developed the exact same problem and I'm about to install new plugs and ignition wires today in attempt to cure the problem. However, I think the fuel filter is probably the real culprit now that you mention it.

[Mad Dog Bodine]

Originally Posted by BlackStealth

My car has developed the exact same problem and I'm about to install new plugs and ignition wires today in attempt to cure the problem. However, I think the fuel filter is probably the real culprit now that you mention it.

Let me know how that works out for you. Like I mentioned, plugs are barely a year old....wires are old however. I will be ordering a fuel filter and getting the capacitators replaced very soon just as preventative maintenance and possibly the cure to my problem. Hopefully its just something simple like that.

MDB

[vandyfan]

just got done with this problem. Change the plugs and if that doesn't fix it change the wires.

[BlackStealth]

I just installed new NGK OEM platinum plugs, NGK ignition wires and fuel filter and the problem is still there. I guess I'll keep my MSD ignition wires since there's not much mileage on them.

I'm borrowing a brand new boost controller solenoid from a buddy for my Greddy Profec, so I'm pretty sure it's not boost controller related.

I changed my ECU caps a few years back, I estimate about 30,000-40,000 KM's ago. For good measure I used better quality capacitors (105C) over the stock 85C. There was no leakage when I changed them then, and last year's ECU capacitor inspection was good too.

My oil cap is leaking so naturally I inspected my PCV valve and it appears to be working so I purchased a new mitsu oil cap instead. Well my new oil cap is leaking now so I'm gonna go ahead and order a new PCV valve (MD153242). I hope a new PCV valve fixes the problem!

[BET-RHD]

Did you get the Oil cap from the Factory? or a parts house? I used a parts house one and it leaked right out of the box..

Jason

[BlackStealth]

Mine's OEM.

[Mad Dog Bodine]

Originally Posted by BlackStealth

I just installed new NGK OEM platinum plugs, NGK ignition wires and fuel filter and the problem is still there. I guess I'll keep my MSD ignition wires since there's not much mileage on them.

I'm borrowing a brand new boost controller solenoid from a buddy for my Greddy Profec, so I'm pretty sure it's not boost controller related.

I changed my ECU caps a few years back, I estimate about 30,000-40,000 KM's ago. For good measure I used better quality capacitors (105C) over the stock 85C. There was no leakage when I changed them then, and last year's ECU capacitor inspection was good too.

My oil cap is leaking so naturally I inspected my PCV valve and it appears to be working so I purchased a new mitsu oil cap instead. Well my new oil cap is leaking now so I'm gonna go ahead and order a new PCV valve (MD153242). I hope a new PCV valve fixes the problem!

Dammit....so no go on the plugs, wires and fuel filter. Hmmmm I am still going to replace my fuel filter and inspect my caps when I have time later this week. I have to order a filter, so when it comes in, I will do both, change the filter and inspect the caps. If the caps aren't leaking yet....I still will probably change them.

Its weird cause boost comes on strong and the car starts to pull, until it passes about 6psi....then it just stutters and boost climbs to 10 where I eventually get off the gas, but its not pulling hard like it should. I don't stay on it hard for fear that I am doing some damage when its stuttering....it also sounds like the exhaust is "popping" when its stutters. Very strange....

[BlackStealth]

Ignition coils might be the culprit too.

[Mad Dog Bodine]

Hmmmm didn't even think of the coils......well I got some other things I need to try/replace first.....then coils will be my next "guess" at what could be wrong with it.

These car's aren't very fun at only 6psi.... .