Boost problem. I'm at a loss

[Eclipse99GST]

Had this boost problem for a while now and can't seem to figure it out. The car will only go to 11psi and then starts bucking and stuttering.

First, I thought it was my AVC-R, so I took it out and put a Hallman boost controller in. That didn't help.

Then I did a boost leak test. NO leaks anywhere. Everything is nice and tight. Ran the car again, same thing.

Then I checked the plugs. Looked great and gapped at .028. Ran the car again, same thing.

While this was going on, I noticed that the wastegate wasn't opening. So, took it off and made sure it was still functional. Seemed good to me. Ran the car again, same thing.

What am I doing wrong. Something is screwed up somewhere. Please help, and if you need more info, I will try my best to answer your questions since this problem has plagued me for a while.

Thanks

Erik

 

[SethA]

Did you replace the plugs with new? I would try that and new plug wires too. I would have thought boost leak but you have already ruled that out.

Seth

 

[Eclipse99GST]

New plugs and brand new NGK wires.

Erik

 

[hellotbone]

Your problem is caused by one of the following;
1)Plugs yes your may look find change them anyways and gap the new ones
2)Plug Wires
3)The Coils }Your manual has the procedure to test this, you have a manual right?
4)The transistor }Your manual has the procedure to test this, you have a manual right?
5)Tuning a rich mixture can also cause the studder misfire you are talking about

Remeber my rep when you fix it with the above sugestions.

 

[Eclipse99GST]

Do you think I should go back to 6's instead of 7's?

Hellotbone: Could you explain the transitor more and how to test it?

Erik

 

[hellotbone]

Do you think I should go back to 6's instead of 7's?

Hellotbone: Could you explain the transitor more and how to test it?

Erik

7's forsure, your mods you should not be running 6's anymore.

The trasistor or ignitor is what triggers the coils and runs the tach etc. Rarely should this cause a problem. I am very convinced it's your plugs/plug wires that are the problem. And at the very last resort the coil. Otherwise look at tuning as a problem.

 

[Herbal Essences]

Check for exhaust leaks also.

 

[DsMWookie]

Try replacing the wires and plugs. I am leaning towards it being the coil if its breaking up under a load and 7's or 6's under 11lbs' really isn't going to affect it under that low of boost.

Does it seem as if the car wants to break up under certain amount of boost or at a certain RPM? Please grab a manual and an Ohm meter and test it.

 

[Mr.Tao]

running too rich will buck studder the car.

 

[Eclipse99GST]

DsMWookie: No, it seems to be at a certain boost.

Sorry to mention, but I don't think it's the wires since it did this before I got them.

Maybe it's my MAFT that's screwed up. Does anybody have some settings I could try so I can get my tuning down pat.

Erik

 

[hellotbone]

DsMWookie: No, it seems to be at a certain boost.

Sorry to mention, but I don't think it's the wires since it did this before I got them.

Maybe it's my MAFT that's screwed up. Does anybody have some settings I could try so I can get my tuning down pat.

Erik

CHANGE the plugs

 

[90blacktsiawd]

The first thing you need to do as a few others have mentioned is change the plugs. After that i would try leaning out your translator. Does it happen at a certian rpm? Or is it just when you hit 11lbs of boost no matter what rpm? If you try to roll onto the throttle and not just floor it does it still happen? Mine was cutting out a 4k which is where i hit full boost. It would studder and buck much like your describing. I ended up turning the fuel down by 35-40% at 4k and sure enough i can pull to redline without a problem. But try your plugs first.

 

[Eclipse99GST]

90blacktsiawd: It just happens at that certain boost. It doesn't matter if i slam on the gas or from a roll, it does the same thing. I will change the plugs and try that. Allentown. I'm about an hour away from you.

Thanks everybody for the replies. If anybody else wants to reply, feel free. It might be a number of things I need to check.

Erik

 

[oldman]

I would like to know how much pressure was the system able to hold and for how long during your boost leak test? Have you check compression yet? If the problem is boost rather than rpm dependent, I tend to think it's either boost leak or compression related.

 

[Eclipse99GST]

oldman: The car was boosted to 12psi with a visual look and hearing for leaks. It took a little bit to get to 12psi and as soon as I stopped filling the car with air, the boost pressure went down quick.

No, I haven't done a compression check yet. But, I only have 57,000 on the car and she is not abused or raced that often. Could it still be off?

Erik

 

[SethA]

Did you use a compressed air source with a regulator or a bicycle pump to do the test? Using soapy water and a spray bottle to make bubbles can identify leaks that are otherwise easy to miss. Old will probably have more input, but it sounds to me like you still might have a boost leak.

Seth

 

[ddavisaf]

It doesn't sound like you're running the boost leak test correctly.
You should be putting 20 psi into the system. It should hold it for a minimum of 30 seconds. Spray soapy water over everything. Your two test points should be the turbo inlet and the throttle body elbow.

Also, get someone to put their ear up to the tail pipe while you run the test and see if it's leaking out air through the tail pipe.

Yes, run a compression test. It doesn't matter how many miles you have, something could be wrong.

NGK BPR7ES plugs gapped at .028" definately.

How is your pcv routed? Stock location or to a catch can? If a catch can you're using a 1/8 npt straight fitting in place of the pcv right?

 

[oldman]

oldman: The car was boosted to 12psi with a visual look and hearing for leaks. It took a little bit to get to 12psi and as soon as I stopped filling the car with air, the boost pressure went down quick.

Are you saying that you were free reving in nuetral to build 12psi or did you perform a boost leak test to pressurize the intake with a compressor/bike pump?

No, I haven't done a compression check yet. But, I only have 57,000 on the car and she is not abused or raced that often. Could it still be off?

Still will be a good idea to check anyway since you're having problems but let's focus on the leak test for now.

 

[ddavisaf]

Are you saying that you were free reving in nuetral to build 12psi or did you perform a boost leak test to pressurize the intake with a compressor/bike pump?


Still will be a good idea to check anyway since you're having problems but let's focus on the leak test for now.

I'll take a back seat this time

 

[gixrman]

Correct me if i'm wrong but your gonna hear air because at some point there is going to be an exhuast valve open to let air escape. Also should'nt the throttle plate be opened during the test?

 

[ddavisaf]

The pressure should technically stop at your pistons.

 

[oldman]

Correct me if i'm wrong but your gonna hear air because at some point there is going to be an exhuast valve open to let air escape.

If you hear air out of the tailpipe during a pressure test it can mean one or combination of the following:

1. Leaky EGR valve.

2. Valve overlap, occurs at TDC between exhaust and intake stroke when exhaust valves are about to close and intake valves are beginning to open.

3. Bent valves.

Also should'nt the throttle plate be opened during the test?

Boost leak test "NO", because the throttle plate is not suppose to close completely so pressure will still pass through. Compression test "YES", to provide free flow of air to the pistons without creating vacuum in the intake manifold area.

 

[SpoOLxExO]

The throttle plate needs to be open when conducting a *Compression test.

What everyone here is trying to get ECLIPSE99GST to do is a boost leak test.

The soapy water and guage from the air source are you only monitors.

The inherent design of a 4-stroke engine means that a valve will be open all the time, so listening out of the tail pipe won't help you track a boost leak down.

This is what I suspect, had a similar problem a few years back.

Turned out to be a huge rip in a coupler that couldn't be seen to the naked eye. Some pressurized air helped me see what I could not previously.

SO...

99GST: you get a new set of plugs and do a boost leak test yet?



P.S. I almost forgot, this is kinda related to the recent posts about turbos not boosting. It is almost always the exhaust side of the problem and not the intake.

Think about it. What happens when a car runs really rich? Boost leak, sputters, black smoke... etc.

If it can't run, then its damn sure not gonna boost.

Turbos that do not spool are from exhaust, just a heads up for people.

EDIT: OLDMAN beat me to it!

 

[Eclipse99GST]

Wow, many questions.

SethA: Iused an air compressor capable of 100 psi, no bicycle pump

ddavisaf: I'm running a catch can. One hose off the one nipple and one hose off the pcv valve. Routed tobgether to a catch can with a breather filter on it. Do I need a straight fitting? Is that my problem?

oldman: Boost leaK Test was done with the car off connected at the turbo inlet.

SpoOLxExO: I will get a new set of plugs.

Does everybody think I should do another test even though that one didn't show any leaks, visually and audio wise? What else can I check?

Erik

 

[hellotbone]

CHANGE the spark plugs, check the coils. Log a 3rd gear pull if you can and let us see it.