Engine idle problem / acceleration hesitation when cold, Throttle body changed now running out of ideas!! Options

[Fujifilm]

HI

I have a problem that I cant resolve, it started with a rogh idle so I cleaned the throttle body etc. That seemed to cure the problem but it came back, I checked vacuum hoses and they "look" ok.

I took throttle body of again and cleaned it same problem. So to eliminate the throttle body and the two sensors I purchased another second hand throttle body with sensors, installed and the same problem so now I have no idea what to look at. I also changed spark plugs and fuel filter.

The symptoms are....

When starting from cold the car is not very responsive, pushing on accelerator nothing happens then suddenly it will go. It does this until it warms up and then drives ok. BUT when driving with low revs it feels jerky. I can drive for ten miles with no issues, stopping at traffic lights etc. But occasionally the revs will drop so low it nearly stalls. When I get to destination and come to a complete stop it sometimes stalls. Leaving it for ten minutes then driving results in no problems.

The main problem appears to be from cold for about 5 minutes.

Can anyone offer any ideas, the car is a 1995 convertible st202 with 70000 on the clock, its got the one vacuum hose on thhrottle body and pre the extra resonator box.

Just add, I dont know when this started, when I purchased the car owner said it run perfectly but he left an egg cup full of fuel in it and it ran out on my way to petrol station, and it was empty as you possibly get! Could this have affected injectors, I would have thought if it was injectors it would do it all the time?

This post has been edited by Fujifilm: Jul 2, 2014 - 7:23 PM

[VavAlephVav]

Change the fuel filter, and spark plugs, dist cap and rotor first if you have not already.
maybe even check the sock/filter on the pump in the tank since its under the back seat and not hard to get to.(maybe check this last)
and a little seafoam in the gas tank is good too.

if that's good look at the way the throttle body is set up, is the throttle opening diaphragm expanding out. There are two set screw on the throttle body, the one on the diaphragm should be set so that the throttle will be further open than if it were contracted by vacuum.
When the motor loses vacuum the diaphragm expands out and keeps the motor from dying. Special Eddy's got a vid showing it on youtube.

https://www.youtube.com/watch?v=C7a0ejq5be8

then also check out the thread I posted on how to Calibrate the TPS if that is not setup right it will act funny.
http://www.6gc.net/forums/index.php?showtopic=93126

[Box]

Bad coolant temp sensor can cause all kinds of trouble. It doesn't cost too much to go ahead and go through the fuel and ignition system to make sure it's ok, just can be a pain to replace the strainer and fuel filter. Probably wouldn't hurt to flush the injectors out either. Then again the coolant sensor isn't too expensive and it's easy to test.

[Special_Edy]

O2 sensor maybe? When you check the plugs is it rich or lean?

[Fujifilm]

Thanks for replys, when I changed the plugs the old ones were perfect. But I changed them anyway. The fuel filter has been changed.

I will change the coolant temp sensor see if thats the problem. It does appear to be temperature related because once its warm the problem does not excist apart the fluctuating idle at stop.

The reason I changed the whole throttle body was to eliminate that and the two sensors. So I know that I am looking for something else. Unless of course I have been unlucky and got another duff one.

Again thanks for replys really appreciate the advice.

My engine is the 3Sge is the TPS setup the same

This post has been edited by Fujifilm: Jul 3, 2014 - 3:13 PM

[Jaybo]

Have you checked your alternator belt?

[VavAlephVav]

According to the manual the measurements for calibrating the tops on the throttle body on the 3sge are the same as the throttle body for the 5sfe.