View Full Version : Car nearly stalls when I hit boost

02-01-2005, 02:02 PM
Hi fellas,

I have a 1990 ST185 GT-Four...

I've been having this problem for a while now. It happens occasionally but not too often - I can still drive it, I just can't hit boost, much :(

Anyway, what is happening is everytime I hit boost in any gear, the car basically stops, and loses its revs... going below 1000rpm. Once this happens I have to shift back and back off the gas a bit before accelerating slowly, making sure I don't hit boost (otherwise it will jolt the car again).

Does anyone have any idea what could be causing this? Someone has suggested maybe its in the AFM, that may need to be replaced - apart from that I have no idea. Any ideas?


02-01-2005, 04:48 PM
Sounds like fuel cut. What kinds of mods are you running?

02-01-2005, 09:24 PM
check your ignition system. Make sure your wires and plugs are good. Gap your plugs to .28-.30. Check your dizzy cap and rotor.

02-01-2005, 09:25 PM
Also check your codes. You have a diagnostics box, bridge TE1 and E1 with a paperclip and turn the ignition on. Your CEL will flash a series of codes. Example 4 flashes a pause and 1 flash is a code 41. A steady constant flash is NO codes. Get your codes and let us know.

I take my statement back, if it falls on its face and drops to 1k rpm I doubt it is ignition. If it boosts and bucks wildly it is ignition.

02-02-2005, 12:35 AM
sounds like fuel cut, overboost or a bad air leak - run a quick diagnostic to check the sensors.......

02-02-2005, 04:02 AM
it can be many things...bad ignition...boost spike...vac leak...bad tps...maf...clogged fuel filter....lose ground wires.....it happened to me...checked all of the above..and ended up being the tps at first...then bad ignition....then loose ground wires...it's really hard to tell so it's best off to start checking one of the above..

02-03-2005, 04:59 PM
check your ignition system. Make sure your wires and plugs are good. Gap your plugs to .28-.30. Check your dizzy cap and rotor.

i thought the gap was like 0.8mm to 1mm??

02-03-2005, 05:11 PM
i thought the gap was like 0.8mm to 1mm??

0.8mm or .31", same thing.

02-04-2005, 09:57 AM
Ok guys, sorry for the late reply, been so busy.

I checked the signal and it seems to give a 34, that means that it's the turbo pressure signal - so most of you are right, fuel cut-off due to high turbo pressure.

What can I do to solve this problem? I'm not running any mods except for the modified intake (K&N Pod etc...)

And as far as I know, I haven't played with the boost - the only thing I've touched is that green valve that comes off the wastegate (I think)...

Any suggestions?

02-04-2005, 10:02 AM
Actually, I've just been reading up. It seems that is my problem, the wastegate valve. Some guy who was fiddling with it a few weeks ago closed it right up, then I noticed it was running like shit, so I opened it back up again, I might have open it a little too far... I will check it and see how I go... I'll post back here.

02-04-2005, 10:50 AM
Well I just took it for a run, drove it fairly hard, it doesn't seem to have the same issue as before. Although now I've tightened the valve up a bit I have noticed a bit of a drop in performance, I spose that's to be expected.

Thanks for the help guys, especially with that diagnostics thing, that will come in VERY handy in the future... :)

Cheers, I'll post back if I continue to have problems.

02-04-2005, 03:22 PM
Glad you solved the problem. If you hit fuel cut in the future, turn off the engine, and remove the EFI fuse for 1 minute. This will clear the code so you can run again.

You really need an aftermarket boost gauge to know what boost you are actually running. Then with a ball/spring MBC or EBC you can adjust boost to exactly where you want it to be.

02-04-2005, 04:07 PM
All I do when I hit fuel cut is turn my engine off while Im driving and turn it back on.

It clears the code on the fly. You dont need to reset the ECU.. It just stores it for refrence.