87 TII.
My Mods.
Turbo Timer
3" MP with resonator
No muffler
Pre CAT still there.

Ok. I get on the free way and smash out.

This also happened before my exaust mod. It doesn't matter what gear I'm in but when I'm at full boost, WOT The car stumbles.

Imagine your driving in first taking off from a stop light going about 10mph then let go of the pedal and tap it, let go, tap it, let go, tap it, let go and your just shaking all over the place. I have great power. I've takin it up to 130mph but couldn't do it at full boost just right below.
(the streeing wheel started to feel light plus bald front tires and ran out of room had to slow down)

I know it sounds like fuel cut problem but sounds and feels more like a slight back fire.

Iv'e been told it could be fuel cut. But those are my only Mods. I don't think I'm running more than 6lbs. boost. I'm reading boost from the stock guage.

I also have a faint exaust leak from the manifold to the block and from the pre-cat to the turbo. But when all this is warm, you can still hear it-but less.

Would an exaust leak as described above give a false reading to the fuel cut thingy as being more boost than what it really is?

What should I check first?

I've replaced the plugs NGK Platinums. Old ones looked very good.

This problem takes my eyes off the road to look at the boost guage. So this problem doesn't happen, I juggle the pedal so boost stays below the very top.

 

I have the same problem with my 3rd gen! All I have for mods is a downpipe. Not even an exhaust. I just got it put back together after doing the vacuum hoses and it just started doing it today. It scares me to run at full boost cause the car lurches so much. I haven't started to poke around in the engine bay yet, but I'd like to find out what might be wrong with your car, so I can check mine as well.

 

If you don't have an FCD or reprogrammed ECU. YOU ARE HITTING FUEL CUT. Especially, with those mods. The stock gauge sucks dick, all the stock gauges suck. Don't trust your engine to that stock gauge.

No, an exhaust leak wouldn't cause a false reading to the pressure sensor, as it reads manifold pressure not exhaust pressure.

I think its unlikely, but maybe your secondaries are SUPER clogged.

 

I'm not sure if your hitting fuel cut or not as I never have. I've been told its like hitting a wall, you KNOW it. Is it just kind of like you don't hold boost and kind of bogs? When I got my TII it would do that, I put on a cone intake and it fixed it. Something to try.

 

You know, my injectors do leak so they may be clogged.

I also have a cone filter set up. I'll try that too.

Damn driving like this is sooooooooo annoying.

 

What would be the process to clean the injectors?
Pull them and soak them over night? week? any special chemical or tools I should use?

 

Have them professionally cleaned and blueprinted. Its the only way to clean them correctly and only costs like $20/injector.

 

What type of shop should I go to get this done?

I stay in CA in the Bay Area. Anyone know a reliable shop for this type of job?

What is meant by blueprint? (injectors)

 

Lucky you. RC Engineering is THE place to have it done.

www.rceng.com

 

Correct me if I'm wrong, but isn't fuel cut for 87-88 T2's @ 5.5psi?

 

Nope, 8.6psi.

 

You are definately hitting fuel cut. All i have is a bonez highflow cat and i hit it. get fcd

 

Your getting 8.6psi with just a highflow cat? Hmm...

 

So ya'll mean to say just a MP and my resonator and my original turbo could hit 8.6 psi?

I'm sure you guys are correct!

Before I did those mods my 7 still had this problem but it was very faint and few & far in between and only once and a while, especially when I used 87 octane gas.

How about advancing the timing lets say to about ~28 or so. Would this help?

 

Sounds like fuel cut to me! I built my own FCD off the fc3s.org site. On a cold night i would hit fuel cut all the time! before i adjusted it. It's pretty soft, hitting a brick wall is riding in a mr2 that hits fuel cut

 

advanced timing with stock fuel system might not be the best idea. If you mod the car any more (or possibly with current mods), you might start detonating. I think you might be real close to fuel cut, if not hitting it already. HOWEVER, you said the problem also occured BEFORE the exhaust, which would mean that it was not fuel cut. I can't see you hitting fuel cut before the exhaust mods. I would look into it further and check plugs and wires. Sounds almost like some fouled plugs that aren't keeping up with all the fuel needed for boost. Just my opinion though, so it might be a little off. I just thought i'd give ya something else to think about.

 

fuel cut is at 1 psi over stock. for s4 its 6.5 for s5 its 8.5. see reted's page at fc3s-pro.com if you don't believe me

 

NO. Fuel cut on a 87turboII is 8.6 psi period. Read the following: http://www.teamfc3s.org/info/articles/fcd/diy_fcd.htm

P.S. I've captured 3.6 volts output from my pressure sensor, to the ECU, when I hit fuel cut. See the graph in the above site.

 

I am experienceing the same thing, but it wasn't happening before I got an exaust leak right at the turbo. I had fixed an exaust leak at almost the same place about a month ago and it fixed it, and now that I have a leak again its back. And yes I have a FCD

 

I had that happen to me before. It seemed kinda random. Turned out that I forgot about the *pill* in the boost sensor vac line when I changed them out. So even though I was below 8.6 actual psi, the computer thought it was higher. So if the vac lines have been changed, you might want to check to see if that pill is inserted in the line.

 

Fuel cut symptoms were happening to me when I first got my car running right. It turned out to be a soft intake hose which was completely collapsing under boost, causing the engine to choke itself at high throttle. Damn those stupid hardware store rubber pcv pipes. They are very soft.

 

Do you have any pictures of this pill?

 

It could be what saabguy said, I have read alot about that, or else it could also be a grounding issue, I know that some times poor grounds can cause thise type of thing.

 

naw, I don't have a picture but it's about this long : |--| with a little hole in the middle (stuffed inside the vac hose). I believe mine was located within the first 6 inches or so from the boost sensor. If you still have the stock vac hose inplace, I believe they marked the spot with a white dot. Just kind squeeze the hose together till you find a hard spot. If you find it, you have the pill in place and you're good to go. If it's not, do a search for "boost pill" or something like that and you'll find a part #. You'll need that # cuz the dealer will have no idea what the hell you're talking about. Good thing is, it's cheap and easy.

Another thing to look at is your fuel filter. Has it ever been replace? If not, might be a good time to change it.
How about the plugs? No more than about 15,000 miles per set. Wires?

Get a boost gauge while your at it. If you like, I got an autometer pro-comp reads up to 20 lbs that I replaced with a 30 pound unit. Was always accurate for me. $25.00+ship

This is the only way to really tell what boost you're running

 

Im in the midsts of finishing my turbo conversion and was unaware of this. Thanks.