jono20

so I got a new car after I crashed my other one. Is a 90 GX.

Ive replaced the plugs, plug wires, o2 sensor, fuel and oil filter changed oil. It idles ok when its warming up. I satret the car cold and it idles about 1500 till its warm, and its solid, but once it gets hot it wont idle at all. id pulses from 750 down below 500, and osmeitmes goes low enough to stall. ive got the idle adjsuted on top of the TB as high as I can, and ive tuned the TPS. I dont know what else to do!!

im getting a code 9 error, which is the thermosensor. could that be affecting it at all? whats the thermosensor actually do?

HAILERS

Check the plug on the water thermo sensor on the BACK of the water pump housing. That is a KEY sensor for fuel control. It's green in color and somewhat rectangular in shape. Make sure it's electrical connector is on.

If the plug is on the sensor, then pull the middle plug off the ECU and either OHM out the sensor or read voltage on the output wire of the sensor TO the ECU. I usually see about 0.4 to 0.5vdc with a fully hot engine. It's the green/white wire. Back probe that wire with everything connected up and a hot engine. Idling.

That should take care of a WATER THERMO SENOR problem. The other problem? Idle the engine with it fully hot. Pull the bac's plug off while idling. If the rpms don't drop when you do....I'd say there is a wire pushed back in that plug or the transistor in the ECU is kaput.

If when you pull the plug off the car dies.....then I'd say you need to start from square one and set the idle. First set the timing with a timing light and bac plug off. Then adjust the idle screw. If that does not work I'd suspect .............................something is amiss.

jono20

does anyone else have any ideas?

jono20

is it possible that it may jsut be overheating? a broken thermosensor leaves the water temp set at 165 degs F I believe, so if it gets hotter than that could it be affecting the idle?

jono20

the plug on the thermosensor is on tight.
just did a compression test, solid 3 wooshes from each face
I pulled the BAC plug off while it was idleing,

the idle screw does next to nothing to help, even when full open it doesnt really help.

again, ive done the plugs, wires, 02 sensor, fuel filter, oil filter, oil change. still nothing.


one thing I DID notice today though.. I replaced the plugs less than 48 hours ago, and I take them out and they are black again. what does this mean?

is it the timing?

jono20

GAHHH where are all the knowledgable people tongiht!~?>

iceblue

Means you are runing rich! Start with timing. Must be idleing at 750. Check the injectors OHM and the AFM per the FSM links found in FAQ.

HAILERS is one of the most knowledgable people on this board. Try what he said to the T.

jono20

ok i went to do the timing today but the guy said it wasnt that. ill do it tomorrow hopefully!

jono20

ok so my timing is good and it didnt help much. is there anything else that could cause me to run rich?

I took the thermosensor from my other car and put it in, I am still getting the check engine light though. what could this mean? is thee problem in the computer?

RETed

Reset the ECU by disconnecting the battery for about 5 minutes.
Error codes are "stored" until you clear them out by dropping power to the ECU.


-Ted

jono20

ok ill try that.

either way, with the new thermosensor in the fan still isnt kicking in. I hvant heard the fan kick in to high gear since I got this car, and I imagine thats why its over heating. it IS the thermosensoor that controls the fan isnt it?

jono20

could the thermostat be bad?

iceblue

This thread was about idle issues. Is it now a over heating thread? You have an electric fan? It has never worked? You put a new T-stat in right? Is your car idleing now?

jono20

I think the idle may be being caused by the car overheating.

the normal stock clutched fan isnt cooling the engine suffieciently I dont think. In my old car I could always heard the fan rev up really louod when the engine got hot, I never hear it in this one. only that satisfying sizzle of boiling coolant

im about to replace the stat, turns out this car doesnt have one at all.

jono20

are the radiatiors in the s4 and s5 cars the same? bc my s5 one looks a lotttt different... perhaps the previous owner replaced it with something else? gagh

bradenscreed

i took the radiator out of my parts 91 and put it in my running 91, and noticed they were different, but havent had any problems, but im in the same boat, idle is crazy and check engine light is on, no tags or insurance yet as i wanna get it right before i spend the cash to get it legit, so can take it anywhere to get stuff checked....just wondering...what might a BAC sensor be?

iceblue

S4 and S5 RADS are different. If your fan hummed loud all the time the fan clutch was bad.

The BACV is a idle control valve. Auto zone should computer check for free. It should be safe to drive but only you know. Search under idle and different issues like eratic idle and so on this is coverd alot so I know there is a ton of stuff out there that you can check out and give us a specifc probablem to work out.

tIIsleeper

What does your temp guage read when it wont idle?

RETed

I dunno...what is a "BAC sensor"?


-Ted