1990 Gt4 Acceleration Problems

[stv_t]

Hi,

I'm having some weird problems with the acceleration on my 1990 GT4 Jap. import. Anyone out there had anything similar

These are the symptoms once the engine has warmed up although neither happen all of the time:

1. After standing at lights or crawling up to and round a roundabout the car does not "feel" right when accelerating away, it feels sluggish and the turbo boost gauge can go up to maximum but there is still no acceleration.

This sometimes goes away after about four hundred yards.

2. Sometimes under acceleration (not necessarliy hard) the engine will cut for a split second, the car will judder, as though a rev limiter has cut in although it may only be doing 3000 rpms, and the yellow engine warning light will come on for about 5 seconds then go out again. Once this has happened it will continue to occur until the engine is switched off.

If 2. occurs I have found that simply stopping, switching off and starting up again immediately will clear the problem.

I have been told by different people so far that this could be the air-flow sensor, the fuel sender unit, the fuel gauge does not work properly so I have one on order, a problem with one of the vacuum pipes. I have checked out the diagnostic codes from the ECU but they do not show anything.

As switching off will clear the problem could it be a problem with the ECU itself, it is still restricted and has not been converted.

Any help or ideas where to look would be greatly appreciated

[Martz]

Not sure if this is relevant or not, but an old car of mine (a ford something or other!!) had what sounds like similar acceleration problems.

That case was down to the automatic choke sticking open.

Does it only happen when the engine has warmed up, or can it be any time?

[dawesy]

just a quick point. you are using superplus or optimax arn't you?

jap cars are designed to run on 100ron fuel superplus/optimax isabout 97 regular is 95!!!

it is possible the knock sensor is detecting knock and retardin the ignition/boost

[stv_t]

Dawesy - Yes I Am using Omtimax or superplus petrol I haveeven added octane booster to the tank and the probelm still happens

Martz - Don't think its anything to do with the choke as it may run for 5 minutes or 1 hour before it may start to show the problem.

It only seems to happen when the engine is hot - And then not all of the time. It also seems to happen in all gears except 1st once it has started -

makes pulling away and getting up to speed or overtaking a bit dodgy as it keeps cutting out until I can switch off and restart.

- Could it be something to do with the throttle position sensor ?

[dosenöffner]

MAP sensor or dump valve sticking. Sounds like over boost.

There is a boost cut on 1st and 2nd gear so you shouldn't really see it in those two gears.

Flush out the boost valve solenoid with some brake cleaner.

[stv_t]

dosenöffner - Thanks for the reply I'll try what you suggest however, could you tell me roughly where these are located. I've only just got the car and have not yet found my way around the engine bay.

[stv_t]

I think I have solved this problem.

I removed the intercooler and the the air box to turbo inlet hoses. Underneath I found that one of the jubilee clips from the turbo to the intercooler was missing and that one of the short vacuum pipes under the air inlet hoses also only had one jubilee clip holding it in place and that the other end was split and had almost come off the pipe.

Bought a new piece of vacuum pipe and two jubilee clips and everything seems to going fine now.

Fixed for less than 3 quid

Thanks for the help - just glad it seems to have turned out to be something so simple.

[dawesy]

hats the sort of problem i like. simple and cheap to fix