Camry Warm Start Hesitation

[ultros_69]

Hi Everyone,

My 93 Camry V6 (205k km) is having difficulty starting after being fully warmed-up. When I try to re-start the engine after it is warmed up (20 min to ~3 hours(worst point) of sitting after a drive) there is starting hesitation and it sounds like only some of the cylinders are igniting until it catches after repeated engine turning (sometimes I add a bit of gas to get it to catch). Cold starts work perfectly and the car never has problems with idling or stalling (runs like new otherwise). It also starts normally up to ~20 min after resting. I have recently done a fuel injector flush, replaced the plugs (NGK iridium), cap & rotor and cleaned the throttle body with seafoam which improved cold starts, but the warm start problem continues. My fuel and air filter (CAI) are relatively new.

I've read that it may be a problem with valves, electrical contacts around the fuel system or ignition (switches/sensors) on other cars but was wondering if anyone had this problem with their Camry or could please suggest any options. It seems like it could be a problem of wire expansion/contraction during a warm vs. hot engine. I was considering changing the plug wires or MAF sensor but do not have money to waste on unecessary repairs.

Thanks for your help!

Alex

[hooRAH]

Any time I have a warm start problem or see one the first thing I would recommend is cleaning the throttle body and idle air motor.

[ultros_69]

I recently cleaned the throttle body and IAC valve with seafoam and this did not correct the problem.

Thanks.

[hooRAH]

Im sorry, I saw the part about the spark plugs, injector flush, and all and must have just skimmed right over that section.

Sorry about that.

[ASG14]

Just because you cleant he IAC does not mean it will work if the sensor itself is bad. Try testing it would be the best guess. I know some people here have done it. There is a certain resistance range I think for it to work.

[Mike Gerber]

Try checking the coolant temperature sensor. Toyota calls this an ECT sensor. It may be out of spec and is telling the computer the engine is always cold. This would allow the engine to start easily when cold, but may be producing a fuel mixture that is too rich to start a warm engine. You will need a DVM and the specs from any manual. There is a generation 3 manual stickied at the top of the General Camry Discussion forum that is available for free downloading. Be sure to check the ECT sensor cold and then warm.

If that checks out OK, I would then check the coil specs. I really am not certain if the 93 V6 still used a distributor; but if it did, it has an internal coil.

Mike

[ultros_69]

Thanks everyone; I will get my mechanic to test these potential problems. Odd that the IAC valve might function perfectly during cold starts, but not warm...

You might be right Mike, but if the ECT was reporting the coolant temperature to the computer as always being cold, would it not hesitate immediately or say 5 min after it is shut down just as opposed to my current situation (after ~10 min)? I should also mention that at 10 min it starts mildly hesitating and at 3 hours (more cooled) it is really choking. When the engine finally catches the rpm's fly over 2.5k, then come down... I believe the car has a distributor. I recently changed the distributer cap and rotor but will also consider checking for an internal coil. Thanks for your help!

[ASG14]

Yeah, the 1993 Camry has a 3VZ-FE. Last year the Camry V6's had a distributor.

[Mike Gerber]

You might be right Mike, but if the ECT was reporting the coolant temperature to the computer as always being cold, would it not hesitate immediately or say 5 min after it is shut down just as opposed to my current situation (after ~10 min)?

I'm not sure about that one. I have seen strange things happen when these sensors got "slightly" out of range. It's best to just check them if you have a DVM. The more I think about your question, the more I think I would lean toward checking out the coil first. I would also check the fuel pump pressure with the engine cold and then again warm. You will need a fuel pressure gage for this test. The coil and the fuel pump have a tendancy to produce problems when they get warmer.

Mike

[davemac2]

you might have a leaky injector which is flooding one of the cylinders after sitting warm like that. If you can, pull the plugs on each cylinder after an hour sitting warm and see if any of them are wet. Are you losing any coolant?

dave mc

[ultros_69]

It's best to just check them if you have a DVM. The more I think about your question, the more I think I would lean toward checking out the coil first. I would also check the fuel pump pressure with the engine cold and then again warm.

I've looked at the parts list for my car and noticed that there is an ignition coil and ignition coil wire. Would it be the actual coil or wire that could be faulty? I will also get the fuel pressure tested...

you might have a leaky injector which is flooding one of the cylinders after sitting warm like that. If you can, pull the plugs on each cylinder after an hour sitting warm and see if any of them are wet. Are you losing any coolant?

My coolant has been stable for 6 months since I replaced a leaky water pump. Oil levels are also stable. Would you smell gas with a leaky injector upon starting? I haven't been noticing the smell of gas in the cabin or around the engine. If it was a leaky plug though, your technique should diagnose the problem.

This is a tough problem as so many components may be at play and its hard to easily narrow one down!

[Mike Gerber]

"I've looked at the parts list for my car and noticed that there is an ignition coil and ignition coil wire. Would it be the actual coil or wire that could be faulty? I will also get the fuel pressure tested... "

It's usually the coil itself that goes bad.

Mike