Low Boost

[DK77]

A boost leak may give the impression of a bad MAF when you test it. I still would recommend doing an intake pressure test before you replace the MAF unless you can borrow one to check so that you don't buy one and have it not fix the problem.

[GreedyTurbo529]

Yeah I was going to do the pressure test, figured Id get 3SXs one Ill test it in a day or too. Ill try the MAF thing now though. What it feels like when driving is a leak, and the car just seems somewhat slower, ever so slightly than what it usually does, and it happened after it did that sputter while I was pushing it hard.

Out of curiosity I know the boost gauge is wrong, but how does it/did it read on your cars? Mine has always stayed at -7 at idle, then it would go up according on how much throttle I put into it though it would stay at the 0 and 7 spot depending on how much throttle, then if I put the throttle mostly down or more it would shoot up to 14. Now its reading nothing at idle, and snaps to about 3 then at WOT itll hover between 10 and 13. Actually it seems more accurate now that I think about it. lol. Doesnt change how the car feels though.

One thing Ive failed to mention was an occasional ruff idle Ive had, happened the morning this issue started as a matter of fact. It would sputter at idle and be low about 600 rpms. Sounded almost like a large cam actually, with what it was doing.

Disconnected the MAF and it seemed to run better, idle too, actually. It still didnt have the acceleration its supposed too, just barely off. But Id assume thats because the MAF wasnt plugged in. Right?

Thanks for all the help so far btw. I really appreciate it.

[dpartinvr4]

now that I think about it, if it runs fine when it's cold, maybe it's the O2 sensors? when it goes into closed loop, it's possible getting a bad signal, but it should be fine then at WOT when it goes open...but just another idea. but if the gauge is reading weird, it deff sounds like a MAF issue.

[DK77]

I don't think he's had a CEL. Or at least I didn't see him mention it. IF the car goes off of what it should see based on the throttle position when you unplug the MAF, then a boost leak would still cause the problem. At any rate, ECU would be the last thing I would try to fix, unless you can borrow one. Start cheap and work your way up.

[J_Parker]

Steve could be onto something, like the leaky caps situation I had a while back that showed similar symptoms. It's not all too hard to pull it out and take a peek inside. I do agree with the start cheap method of troubleshooting though. Any mention of timing? Check to make sure there's no crud built up on your trigger blades, intermittent timing flutters can cause issues like this from time to time.

[DK77]

Agreed, checking the ECU for leaking caps is free except time. Have you had a fishy smell, some guys that have their caps leak say they had a fishy smell. My ECU actually burned and I had smoke all over the car. That was easy to diagnose lol.

[GreedyTurbo529]

Get one 3S to keep the other running. I understand that phrase now. lol.

What sort of caps are we talking about? Im a bit lost on this one. And I havent smelled any fish lately.

And should I put a volt meeter on the MAF? Can anyone find how to test it and what it should be reading. Im currently looking it up on that other site, and Stealth 316, but you guys may already know.

[GreedyTurbo529]

Ive got a good question. I was checking the other place, its like a 3S library. And found these comments and others like them in a few threads.

... everything running correctly, if you pull the MAF on a idling car it should stall.

... if you pull the MAF and the car doesn't stall then it could be an indication of a pretty large boost leak. A compression check would be the next step.

... sounds like something might have gotten loose when he "slightly accelerated" to pass that car. But if you pull the MAF and you don't stall, then a compression check is the proper next step. But in reality, it should have been the first step.

Thing is, the ECU will do it's best to compensate for the leak so testing based on your idle is just silly because the computer could be masking the issue.

How right is that? Sound like the path Im going actually.

[J_Parker]

Back onto the leaking caps, just so we're clear on them. They don't always stink when they go, sometimes it's a slow leak that eventually just gives. When they go they can cause issues to that similar to a boost leak, like unplugging the MAF to only have the car remain running.

[DK77]

I didn't have the fish smell, so don't think that you have to. My car had no issues until one morning I backed out of the driveway and the car died. I started it again it died when I started moving. Tried one more time and then smoke started pouring out from under the dash. I exited the vehicle quickly. Never had a fishy smell. After I got the new one I thought I did sometimes but it has worked for over a year.