I recently replaced my water thermosensor and it resolved my on going hard start and rich issue. Now, about a month or two later, the problems are starting again exactly like before. I wouldn't put it past an Autozone part to fail in 1 month, but is there an easy way to check?

I would be very curious to see what temp the ECU is seeing, as well as any other inputs (such as the knock sensor). I am convinced my problem is related to too much fuel and all of the mechanical parts of the fuel system are working properly (injectors were just cleaned and flow tested, and I put in a new fpr).

For anyone that wants to give any other suggestions here is exactly what is happening:

- at idle I notice my a/f on the rich side (before the problem started it flashed all over the place at idle)
- when I start it cold it runs rough but soon clears up, it clears up quicker if i blip the throttle.
- hot starts are hard, I usually have to crank it several times and give it full throttle to get it to start. Once it does, I need to apply light throttle for 10 seconds or so to keep it from stalling.

No smoke at all. Rear rotor is 90 on all 3 faces. Front rotor is 95 on all 3 faces. At idle (900-1000 rpm) vac is -15psi

Once the car is started it runs perfect (although I think it runs rich due to decreased fuel economy).

In an attempt to solve the problem I've recently replaced the plugs, plug wires, fuel pressure regulator, water temp sensor (which fixed it for about a month as I said above), the vaccum lines in the rats nest, and I had the injectors cleaned/rebuilt/flow tested/ and leak tested. I also tested the water temp sensor (which checked out ok, but replacing it solved the problem for a month), the fuel temp sensor, the intake air temp sensor, the TPS, and the MAP sensor. All of which checked out ok.

Advice and ideas are greatly appreciated.

Thanks,
-Charlie

 

you'll have to find the specs on the part you installed...convert resistance -> temp reading...using an OHMs meter probe the two wires on the back of the sensor/connector.

 

Was this problem fixed? I too am having hard starting problems when engine gets hot. The engine was just rebuilded and it has 400 miles on it (not broken in yet). I also have the auto zone thermosensor as well.

I have no other problems what so ever. it idles fine and it can start very easy when it cools down.

Thanks

 

seals take some heat cycling and wear before they fully "seat"

Also, ECU's have coolant correction maps...with rebuilds, sometimes the motor can have different characteristics, and coolant temp maps need tweeking...

do you have a stock FPR solenoid valve?

 

yeah stock FPR and the solenoid as well... I've been suspecting it might be a sollenoid but haven't had time to check it yet.

The problem is when it's actually cranking it sounds like it's really weak. It doesn't just crank and start... i have to crank it and hold the key cranking until it starts up... When it starts then it's all well.

 

how much voltage does your battery supply? underdriving the ALT?

Sign of a weak battery, when your battery is heat soaked...it doesn't hold charge. You know how your grandma put batteries in the freezer???

 

I have one of those dry cell batteries PC960. It's relocated to the rear bin. I do have Greddy pulleys on the WP and ALT.

Thing is... i never had this problem before. I had all these same mods before and haven't had the problem. The only difference between this rebuild time was that i replaced a clutch, i broke the FPR solenoid and replaced it with the one i had from probably EGR valve or something else. That's why i said it might be the sollenoid but i'm not sure if it will cause that kind of problem because some people remove the solenoid alltogether and dont' get hot start problems.

 

well 400mi isn't alot for an underdriven ALT charge a little dry cell that's been sitting for awhile...give it sometime and monitor the voltage

 

I have the gauge for voltage... it shows fine. The battery has been charged over the period when the car was down. It held perfectly at 12.5, 6 or so of the car.

 

I, too, have a PC960 in the rear bin and a Pettit (underdrive) pulley. No problems here; even after the car has been sitting for a couple of weeks.

 

Yeah i know the battery is good. It's probably something else.

Thanks