Huge Hesitation And Idle Problem, R33s1

[MBar93]

Hey all

My car has been hesitating while accelerating, to the point where it will choke severely under load. It is also struggling to maintain idle, which fluctuates and will drop to about 500 and the engine will nearly stop running. Somebody suggested my tps may be the problem so I tested the tps with a multimeter. I've read that with the throttle closed, it should read about 0.4-0.5v, and at WOT it should read around 4.5v

At closed throttle I'm getting a reading of 0.36, and at WOT I'm getting 4.21. Just needing some interpretation, is this sufficiently low enough to assume the tps is the fault?

Some extra info that might be helpful: I noticed a few times last week after starting up it would idle unusually high (around 1800-2000rpm) on cold startups. Also while trying to accelerate the engine makes a whining sound before it chokes and goes nowhere. I've also noticed that for a while the idle would fluctuate a very tiny amount, barely noticeable unless you watch the needle very closely.

Edited November 21, 2015 by MBar93

[89CAL]

Whats done to the car? Have you done the simple things like changed fuel filter, checked/replaced spark plugs, checked timing with timing light?

Start with the basics and go from there. You might find something along the way

In regards to the TPS. There are two parts to it. One is a switch and one is a potentiometer. The recommeded voltage for the potentiometer is 0.44-0.46V or so, This is easy enough to adjust. The switch should be closed at idle from memory and then open off idle, I'm pretty sure they are a 2 pin plug

Does it smell like its over-fueling or blow black smoke? You may have a boost leak as well

[MBar93]

Whats done to the car? Have you done the simple things like changed fuel filter, checked/replaced spark plugs, checked timing with timing light?

Start with the basics and go from there. You might find something along the way

In regards to the TPS. There are two parts to it. One is a switch and one is a potentiometer. The recommeded voltage for the potentiometer is 0.44-0.46V or so, This is easy enough to adjust. The switch should be closed at idle from memory and then open off idle, I'm pretty sure they are a 2 pin plug

Does it smell like its over-fueling or blow black smoke? You may have a boost leak as well

It's definitely overfueling, it smells so rich, even more so than normal since it runs pretty rich normally. No smoke at all however

I've changed spark plugs fairly recently. I'll check the fuel filter shortly. Not quite sure how I would go about checking the timing

[89CAL]

timing light, get a spare plug lead (or buy a cheap one from supercheap) then put the lead between the plug and coilpack number 1 (may need to stick a bolt or something in the coilpack to make contact with the coil and the lead) then put the timing light on the lead. Check timing, should be 15 +/- 1 degree at 650rpm. It says to disconnect the throttle position sensor in the manual I have, I'm pretty sure this locks the timing.

If the car is over fueling I would double check your plugs, they may be fouled anyway, check for boost leaks and clean the AFM (maybe even check for dry solder joints) The info is on here to do all this. go to google and search that way - "what you want to search for " site:www.sau.com.au

[zac.r32]

Possible air flow meter problem. if the car stars to miss, and turn off while idle, AFM is your best bet. I have a similar problem, and so far, every similar story i've read seems to be a dodgy air flow meter. I also got the error code for AFM while getting it tested. I'm still yet to fix it and find out if that was the problem though.