desperate for help!! lots of clues...

[jdavison10]

so Ive been having a significant issue with my car for about a month now which i absolutely can not figure out. no garages around where i live even want to look at my car so it looks like im on my own with this one.

the car is a 92 vert with a redtop sr20det.

the issue: the car idles rough. stalls out when coming to a stop unless i feather the gas pedal. boost gauge will show boost when it is built but no vacuum. (at idle the boost gauge reads 0) my wideband is reading --- so it is literally running so rich it isnt able to be read. and finally, the turbo sounds a lot louder, almost sounds like it is being over worked.

recent work: my radiator recently cracked so it was replaced with a mishimoto radiator and samco radiator hoses. a cracked fuel line, and a leaky coolant line underneath the intake manifold were also replaced. the issue arose after this work was completed, ran fine prior. other work done before the radiator/etc was a new clutch, and an aem wideband installed.

i have changed the plugs, checked the maf, checked all vacuum lines as well as couplers and intercooler piping/intake. nothing is leaking. the car still has the stock t25 and the stock maf.

any help would be greatly appreciated as i seem to have run out of ideas at this point. thanks in advance!

[ultimateirving]

Boost leak. Search google or the forums for boost leak tester.

[blkvrtswp]

Intake manifold leak. Check your intake manifold to head gasket. May have been displaced when you worked on the coolant hose. And IACV & TB gaskets too. something's leaking.

[jdavison10]

so i sprayed everything down with soapy water and gave the car a couple of revs to try to find a boost leak. i found absolutely nothing. i did notice that when i would give it a rev i could hear the turbo working really hard through the intake. i re-checked the o2 sensor for the wideband and the maf. still no luck. im getting pretty irritated!

[dbeiler]

boost gauge will show boost when it is built but no vacuum. (at idle the boost gauge reads 0)

Are you saying your gauge is incapable of displaying vacuum? Or are you saying you have 0 vacuum at idle?

If you have a low idle and running rich, it's not a vacuum leak problem. It's starving for oxygen. IACV would be the primary suspect. Does it run fine if the throttle is cracked open a little bit?

Verify the IACV is opening. Better yet, check and see if somebody left the electrical connector disconnected while working on the coolant leak.

[jdavison10]

So at idle my boost gauge reads 0 instead of vacuum. When I accelerate the needle goes down to about -20 vacuum instead of reading boost. My boost gauge has always accurately read vacuum and boost so I don't believe it is a faulty gauge. Doesn't make sense that I would all of a sudden have an issue with my cars performance and have my boost gauge acting up at the same time. I just noticed this last night because I haven't been driving the car. I did look over the iacv and everything seems to be correct with that.

[cotbu]

i don know your setup , but either there is a major boost leak or you have your boost gauge installed wrong or both. When you start to accelerate the throttle is open and you now receive a vacuum signal. It could be hooked up correctly, and have a clogged line, but that could be considered hooked up wrong too.

You should do a boost leak check with compressed air in the piping. Not using the running engine to preform the test, why the vacuum might be sucking the soapy bubbles in and you may not notice them.

a boost/vacuum leak does fit your symptoms, a faulty iacv would'nt cause the zero vacuum if you're able to idle. you may have other issues, but these are the obvious ones.

[jdavison10]

my boost gauge has been installed and working fine for 3 years now so i dont believe the gauge is the culprit. when i am coasting or idling at a stop the gauge reads 0. when i start to feather the gas to accelerate in gear the gauge drops to -20. when i put my foot in it, the gauge does build boost. ive never seen this issue before.

[dbeiler]

Now it sounds like your timing chain jumped a tooth (or more) on one of the camshaft gears. This will create intake and exhaust valve overlap. It'll idle rough and allow freshly injected fuel to exit out through the exhaust valves during the overlap. Hence the rich A/F at idle. Does the A/F return to a normal range while on throttle? Raising the engine RPM will reduce the noticeable effect of valve overlap and the engine will appear to function normally.

It's just a hunch, but I recommend removing the timing covers to verify engine mechanical timing. If it keeps jumping teeth you'll eventually end up with bent valves.

Doesn't hurt to hook up a different vacuum gauge in case yours is faulty. Do a cylinder compression test and, if necessary, a cylinder leakdown test.

[dbeiler]

Valve overlap would also be the reason you can hear the turbo through the intake. Check the engine mechanical timing.

[cotbu]

my boost gauge has been installed and working fine for 3 years now so i dont believe the gauge is the culprit. when i am coasting or idling at a stop the gauge reads 0. when i start to feather the gas to accelerate in gear the gauge drops to -20. when i put my foot in it, the gauge does build boost. ive never seen this issue before.

I explained what was happening and what you should do. I know you seemed to think the boost gauge being hooked up wrong is the point I was making but no it was the boost leak!


Now it sounds like your timing chain jumped a tooth (or more) on one of the camshaft gears. This will create intake and exhaust valve overlap. It'll idle rough and allow freshly injected fuel to exit out through the exhaust valves during the overlap. Hence the rich A/F at idle. Does the A/F return to a normal range while on throttle? Raising the engine RPM will reduce the noticeable effect of valve overlap and the engine will appear to function normally.

It's just a hunch, but I recommend removing the timing covers to verify engine mechanical timing. If it keeps jumping teeth you'll eventually end up with bent valves.

Doesn't hurt to hook up a different vacuum gauge in case yours is faulty. Do a cylinder compression test and, if necessary, a cylinder leakdown test.

More likely the chain was installed wrong, there's too much metal for the chain to get enough slack to jump, and if it managed to jump 1 tooth or 2 it would probably continue to do so because hey what's stopping it. So with all that yeah timing could be retarded and run like ass but I would consider having no vac running like ass or the struggling feeling to make boost like ass as well.

Do a boost leak test, verify timing and comprehend.

I actually want to see a video of this car running now, can the OP make that happen?

Sent from a Highly Tuned Note 4.5!!!

[jdavison10]

I'm still pretty new to this forum. How would I upload a video?

[kruked]

I'm still pretty new to this forum. How would I upload a video?

YouTube


STPDMSSGLNGTH

[jdavison10]

https://www.youtube.com/watch?v=8SA61MSRnBs

https://www.youtube.com/watch?v=8M5RGLo23RA

the first video is the boost gauge reading 0 at idle. then you can see if fluctuating to vacuum as i feather the gas, then pin to -20 upon light acceleration, then to about 10 lbs of boost when i get on it, and back to 0 when i come to a stop. it is kind of hard to make out because of the sun.

the second video is of the intake and how much louder the turbo has gotten since this problem started.

thanks again

[NOLAGG]

https://www.youtube.com/watch?v=8SA61MSRnBs

https://www.youtube.com/watch?v=8M5RGLo23RA

the first video is the boost gauge reading 0 at idle. then you can see if fluctuating to vacuum as i feather the gas, then pin to -20 upon light acceleration, then to about 10 lbs of boost when i get on it, and back to 0 when i come to a stop. it is kind of hard to make out because of the sun.

the second video is of the intake and how much louder the turbo has gotten since this problem started.

thanks again

Where in NY are you from? Definitly do the boost leak test. Any smoke coming out of the exhaust?

[Kingtal0n]

you have the boost gauge on the wrong tb port. One of those ports only applies vacuum when you open the tb. that is the one you have your gauge installed to by accident.

A wideband pegs to 10:1 when the engine is "too rich to read". If yours is showing "---" then you have an exhaust leak and it is actually showing lean because it is picking up atmospheric oxygen.

Finally, the stalling when coming to a light is your open atmospheric bypass valve allowing air to exit as your engine decelerates causing an excessive rich condition which stalls the engine by lowering rpm.

[jdavison10]

I'm from Plattsburgh, ny and I don't see any smoke from the exhaust.

[cotbu]

Here we go, if you told the truth hereMy boost gauge has always accurately read vacuum and boost so I don't believe it is a faulty gauge. Then there's only a few things that could have happened, lets name a few. the line is clogged, the line has a hole, the line came off. You need to check this yourself. Most of your problems could be solved by checking this one thing. NY stay taking L's like Florida!

A wideband pegs to 10:1 when the engine is "too rich to read". If yours is showing "---" then you have an exhaust leak and it is actually showing lean because it is picking up atmospheric oxygen.

I don't really want to get into semantics, but whatever shitty wb he has probably AEM the --- is usually on both sides of the gauge too rich or too lean. Based on evidence that most likely supports a boost leak/vacuum leak, we can assume that he is rich because of that. Why Mafs! Not saying he doesn't have an exhaust leak.

[steve shadows]

Get the biggest modded ecigarette you can and blow loads of vape into the intake manifold through a vacuum line. See where it pops out the other side.

Otherwise you can buy this:http://equiptool.com/i-17360191-redline-smoke-pro-kit-95-0003b.html?gclid=COGymNyw9MYCFYqPfgod8bgLnw

Boom.

[kane01]

Sounds like it would probably be good for you to sell this car. Maybe get something a little less tunerish. Maybe an escort wagon or yeah i got it, astrovan. Come on man, if you can't figure it out just start stripping crap off the motor till you find something wrong. Process of elimination is the only way to do it. Get the intake off and check everything then go get drunk and pass out. Then get up and check it all again. FYI pretty sure if you were confident about a setup you dont really need a boost gauge. Thats why they make controllers. Your gonna hit a freakn tree trying to watch your boooosssstttt gauge. Oooooohhhhh get outta that car, get out before you die.

From your moms basement / using hacked rotary phone