Hi all,
Was having a few problems with my car idling a bit high and I thought my FSU might be on the way out since it was saying I was down to 1/4 of a tank when I thought that was impossible with the amount of driving I'd done.

Apparently not.

Anyway - I am wondering wtf is going on with it, it's running VERY rich - you can smell it, not smoking though. Oddly enough. Can smell it when you are sitting at a set of lights or something too.

I am thinking something is awry here a little more than TPS. I was due to have a look at that regarding the high idle, also planning to do a full tuneup in the next few days hopefully if not, next week or so. Those plans have been accelerated due to this latest development.

It runs like a bit of a pig in lower RPM but once it gets higher goes off like nothing else. I have been reading other posts and wondering if it's possible the engine coolant temp sensor is shot. And whether it is worth replacing that when I do the thermostat/flush radiator/air filter etc. anyway. I presume being in Australia that it will be expensive but what needs to be done gets done.

I am looking in the FSM and can't find anything regarding an ECT however I find references to a water thermo switch. I am guessing this is one and the same thing since the water thermo switch seems to perform the function of activating at 97C.

Any help appreciated here, can't afford this fuel if the prices go back up, lol.

-Sean

Edit: Specs

Series 4 (1988)
Turbo
69,000KM's
5" Cannon Exhaust
Cats are attached
Stock boost
FCD (Was installed by previous owner and WAS running more than stock boost I believe)
Stock airbox

I think that'll do it.

 

have you checked the pulsation damper on the fuel rail. if you can smell fuel, i would definitely check it.

 

Didn't think of that no - I will check that too. I would've thought if it was a pulsation damper problem though I'd be smoking like crazy?

The idle is smooth too - again I thought it'd be really all over the shop. The only odd thing is I can hear low sort of popping noises, I figured it was afterburn. Would definitely suggest richness. Will get a video up if it helps.

Sounds like brrrrrr puff puff brrrrr puff puff puff brrrrrr puff brrrrrr etc.

Will take a video with sound. Will probably explain it better, although I have asked and apparently this sort of dull puffing is normal, so I'm not to worried. Also the fact it still goes like a bat out of hell helps alleviate my concerns a bit :P will check pulsation damper when I do everything else.

Thanks,
Sean

 

Ah man, if you look in the FUEL AND EMISSIONS section of the FSM it shows how to check out the water thermo sensor. But ignore that checkout. It's not worth the trouble.

You can do better than that check. Just get your meter out and backprobe the green/white wire of the water thermo sensor at the ECU plug. Start the car up cold. Then watch the meter as the water fully warms up. It should gradually go down to approx 0.5vdc when fully hot. Its hard to say where it will start out because we don't know the water temp of your car when cold, but that does not matter as long as the voltage goes steadily down to the half volt area when fully hot. Usually it'll start out b/t 1-2vdc and gradually go down to the .5vdc.

IF the voltage starts out around 5 vdc, then the plug is off the sensor or one of its pins is pushed back inside the elect plug.

The smell of fuel could be the lack of a charcoal canister in the engine bay.

Take a timing light to the thing to make sure it's right.

 

Righto - will take a meter to it soon as there's some form of light around and see if that's the problem. If not, well. ****.

I am getting the parts ordered in to do a tuneup on my car (nowhere here keeps them in stock due to the uncommon nature of my car) - I priced a Dayco thermostat for it, at about $30aud, the OEM one is about $100. I need to know if it is that vitally important to get the OEM one, in which case I will, however they also want 2 weeks to get it in. So thinking it might be a good idea since I want to replace it anyway to just do it with the cheaper non OEM one and replace it with an OEM one down the track. Since they can get that in in 1-2 days.

Still wondering about the high idle but I'm gonna take a meter to the TPS as well as the water thermo sensor and see if I can work that out. I don't think there's a vaccuum leak but if there is, well then I'll worry about it then and start searching. More concerned about the car running so horribly rich it's using an insane amount of fuel, really doesn't seem like a good thing.

Thanks,
Sean


Edit: Is it the water temperature switch I'm testing, or the water thermo sensor that controls the cold start enrichment?

 

Water thermo sensor on the back of the water pump housing. Green in color. Two wire outfit.

Water temp sender near the oil pressure sender/oil filter area is a harmless outfit that does not interface with the ECU in any way.

If you have a leaking PD or leaking fuel line, then jumper the yellow fuel pump check connector and turn the key to ON. That causes the fuel pump to run continuously. So let it sit like that for twenty minutes. If there is a leak, you should see fuel dripping on the ground after twenty minutes. No dripping equals no leakage.

 

Definitely no fuel leaking onto the ground - that I can confirm. Had the car sitting several times for 10 minutes or more idling and never any fuel left on the ground.

High idle, and extreme fuel usage that I know is from running rich, so far these are my things to test/look for:

1) TPS
2) Water thermo sensor
3) Will have to check again but fairly sure thermowax is gone, if not, will check that

I'm thinking it's probably a combination of the TPS for the high idle and the water thermo sensor for the running rich phenomenon. Will take meters to everything ASAP though and find out. Timing light is an idea, but I think the timing is fine.

Thanks,
Sean