Friends,

I am experiencing (intermittant) starting problems with my 95 Explorer XLT. The problem comes and goes and seems to only happen when the truck has been driven...like when running around town. All will be fine and then I will get in to start it and it will simply turn over endlessly....like it is not getting gas. This might happen 1 or 2 times a week. It will just turn over and over and over and never crank. Other times it is fine. I have changed out the IAC just incase that was it and it still does this.

Any suggestions....anybody else have these experiences..

Thanks,
Dorian LaChance
dlachance@dclcreativeservices.com

PS A mechanic said he was pretty sure it was the Throttle Position Sensor. He also said I would not be able to replace this myself as it would need to be adjust by computer when installed. Any thoughts?

 

The first thing to do is to find a new mecanic. Any computer learning that needs to be done by installing a new TPS will be accomplished by disconnecting your battery for 5 minutes. That will clear all adaptive strategies from your PCM forcing it to relearn it's idle. The default idle though is still pretty close to perfect. Unless your mechanic was going to replace your TPS for free, it looks like he just wanted to make more money off you. Disconnect your battery. Remove the connector and the two screws that hold the TPS to the side of the throttle body and put the new on in it's place. Reconnect your battery (unless you swapped sensors in less than 5 minutes in which case give it a couple more minutes).

 

Have you pulled the engine codes yet?? If it's a bad TPS, the codes should reveal that. You might also want to consider the fuel pump relay.

Mike

 

I think you need a new mechanic too. The TPS can cause problems when it is bad, but this isn't one of them. You didn't say when the engine acutally started during those 1 or 2 times a week when it cranks on and on. Did it start the very next time you tried (as in a few seconds later) or did you have to wait for hours before it started again? If it started the very next time you probably have a fuel supply or fuel pressure issue to look into. If it takes waiting for the engine to cool down for hours it may be electronics related. The computer uses the TPS for input after the engine starts not during the start sequence. Actually, when you first turn the key from lock to on the computer will look at the TPS voltage for a closed throttle reference voltage (ususlly between .45 and .98 VDC) and command the idle from that reference. If the engine is cold the computer will command a high idle (around 1200-1500 rpm) and after the engine is running start looking at the TPS for demanded throttle. If the engine is warm (using the water temperature in both cases) low idle will be commanded but the sequence is the same thereafter. In any case, the engine should start. If the TPS is bad it may misbehave as you go through the power range due to bad spots on its variable resistor, you may have no throttle response at all if it fails open or shorted (resistance at infinity or zero respectively), or if the wiper fails in a fixed position you will have a fixed throttle setting where it failed with no response to human input. None of these is what you describe.

 

Thanks everyone and Michael Skerrett, you have been a great help....

FYI, you usually have to just turn the key off and wait a minute or so and then try again and it will start. Yesterday I tried it like this over and over and had to wait about 15 minutes. That was the longest I have ever waited.

I changed the Feul Pump Relay last night so I am waiting to see if the problem occurs again. In the mean time.....any suggestions would be apprectiated. Like where to go next if the relay didnt fix the problem...

Thanks,
Dorian LaChance
dlachance@dclcreativeservices.com

 

Well.....it wasnt the fuel pump relay.....

What next??????

Dorian LaChance
dlachance@dclcreativeservices.com