4agze hard to start and then stalls

[mic*]

Check for normal (dont ask me what value that is) resistance accross the coolant temp sensor, though it should throw a fault code. If its buggered its not unusual for things to be fine until its warm - its at the point where your engine is not cold, yet your sensor reports to the ECU that it is still that funny things can happen with fueling and idle.

I would also check the IACV / ISCV thoroughly. Firstly just see how it affects your warm engine idle when you pull the plug off. It could be that the valve is physically sticking on the inside or the water is fouling the electrics. Once again would expect a fault code as you say (unless it is a physical problem with the valve - water can gunk up with oil from PCV system)...

[wiso]

if the temp sensor was saying that its still cold it would just be idling higher and running rich, no biggy

hmmmm a new dimension to the problem, i replaced the dizzy cap and leads, and it has made it heaps worse, now it won't idle at all even when cold, it just dies straight away, tried the old cap an leads again and it would go back to idling till it was warm.

ohh well i have tried everything i can think of, its going to an auto elec tomorrow for diagnosis.

[mic*]

if the temp sensor was saying that its still cold it would just be idling higher and running rich, no biggy

hmmmm a new dimension to the problem, i replaced the dizzy cap and leads, and it has made it heaps worse, now it won't idle at all even when cold, it just dies straight away, tried the old cap an leads again and it would go back to idling till it was warm.

ohh well i have tried everything i can think of, its going to an auto elec tomorrow for diagnosis.

Funny you say that coz i would have agreed, but i have done EXACTLY what you just said (replaced dizzy cap only) on a RB30 - and had exactly the same thing as in prob gets worse. Now that must just be coincidence, but the problem was very simillar, the car would just cut out on idle sometimes when warm, and if you wanted to take off you would have to rev it up a lot. Sometimes it would be a real bitch to start afterwards. Sometimes it would not start at all. After i replaced the coolant temp sensor it was fine.

[wiso]

wow, you make some very valid points there mic, i'll give that ago as soon as i get my meter back from my mate. if thats the cause, it shouldn't be too bad

[mic*]

I must say i was amazed when the problem disappeared. Not the kind of symptoms you would expect (i would expect exactly what you said)

Obviously when it conflicts strongly with other sensors inputs to the ECU, stranger things can happen...

[limbo]

You could of fouled the plugs with the water. Try taking them out and giving them a slight clean. Also clean the dizzy. Worst thing it might be could be the injectors got wet and after they dried its put still has some dired residue. You might need to get them cleaned.
Alst time i washed my engine it was the injectors and the way i fixed it was drive it really hard while it was wet until the problem went away.

[wiso]

ahh sorry limbo, but that can't be the cause the plugs are fine, already looked, and it won't be the injectors as she still drives normal when it rev her, just she won't idle by herself

[myne]

My ecu has a loose wire or a possible problem that causes it to not get a cranking signal until the CAS tells it it's running. Checked the ecu for codes?

[takai]

Yes, myne, read the thread. No codes are produced.

To me it sounds like a bit of water in the ISCV. Because when the car is warming up the ISCV is 100% open, but when the car is warm the ISCV closes, except at idle. This is the same issue which people with frontmounted intercoolers on GZEs have. Basically the ISCV cant respond fast enough to the change in vacuum within the manifold and therefore it is starved of air and stalls.
I would be looking at what has happened there, maybe some water has ingressed and isnt allowing for a fast repsonse to the change in vacuum (since you wouldnt have a large plenum issue). Or possibly some wiring has gotten slightly wet.

[wiso]

i guess the only real way to find out if that is bung is too pull the iscv off the throttle body. today the car is at dynotune getting a diagnostic, so i get a break from it for the last 4 days. if they can't sort it, well i don't know, will keep you informed

[takai]

Yeah, there isnt much you can do apart from play with the ISCV. Ben Wilson might have a spare one off his manifold somewhere.

[wiso]

yeah i was thinking that since he doesn't use the stock setup, i'll wait to get mine off and then i'll be in touch with him

[1200det]

I would also be looking along the lines of the Water temp sensor , Dont be surprised when you find out there close to $200 from Toyota

The girlfriends MR2 had similar issues although she would need to crank it for a good 10 seconds in the mornings to get it started but also had idling issues when hot , replaced water temp sensor and all issues resolved.

wow, you make some very valid points there mic, i'll give that ago as soon as i get my meter back from my mate. if thats the cause, it shouldn't be too bad

[wiso]

damo hows the availability on a temp sensor for the 4agze, are they easy to get or long order?

[1200det]

damo hows the availability on a temp sensor for the 4agze, are they easy to get or long order?

Only a few days turn around to order so could have one here by Monday , Cost is a tad over $200