Roadart

I have been struggling with a gremlin for about 6 months now, I was getting a Code 15 and when the car was warmed up it would suddenly start hesitating and would die.

I replaced the sensor, plugs & wires, ignition module and none of them helped. Last week I opened the gas tank to add some stable and noticed that the rubber seal was all cracked on the filler cap.

Long story short, I replaced it and all my problems seemed to have disappeared, would a bad gas cap possibly be the cause of these issues?

Thanks,
Kevin

Dave89IROC

what year PCM you running?

Roadart

The chassis is a 93 and the engine and PCM are from a 95 transam.

It has a PCM4LESS tune, the car ran great for the last two years, about september last year I started to have the problems described above so I parked it for winter.

Over the past few months I have replaced the temp sensor, flushed the radiator, replaced the plugs and wires, replaced the ICM and installed an aftermarket ignition. I would get a code 15 but no check engine light and the car would suddenly without warning shut off.

Last week I got a check engine light but only a code 15 (temp on Scanmaster was -40). I replaced the gas cap and added some Stable treatment and all of a sudden the car is not throwing a code and is driving great. When I parked the car for winter I added stable, could it have been bad gas, or does the gas cap have something to do with it?

I am just wondering if its fixed. Thx for the response.

Dave89IROC

code 15 is foe the ECT(temp sensor in the water pump), you either have a bad sensor, connector at the sensor(very common) or wiring to the sensor


if the PCM sees -40, it will keep adding way too much fuel, so fix that first

to check the wiring, unplug the connector, and jump the pins(paperclip works good), wires jumped will read reallt high on your scanmaster

use a ohm meter , if you have one, on the sensor, at around 70 degrees, it will read somewhere near 3500 ohms (see here for other temps http://shbox.com/1/4th_gen_tech2.html#ect )

to check the connector, have someone watch the scanmaster reading while you wiggle the connector at the sensor, it will go from -40(open circuit) the the proper temp reading

Roadart

Thanks, I have checked the wiring and everything checked out as you said, and I also replaced the sensor. The car is running fine, once I replaced the gas cap, the car literally transformed and is running great. I was just wondering if the gas cap matters that much.

Currently the sensor is reading properly, I am glad its fixed (for now?) but baffled by the apparent fix.

Again, Thanks for your replies

Injuneer

The gas cap can not cause DTC 15. There is no diagnostic in OBD-I to check for the gas cap seal, like there is in OBD-II, so the gas cap can't even cause a code. Hard to understand how the cap could cause it to run that bad.

Roadart

Sorry, I should clarify, I know what the code 15 is, and replaced the sensor, checked wiring and so fourth.

I didn't think the gas cap had anything to do with my problem, thanks for your help, I just thought it was odd that all my little issues disappeared when I replaced the cap and/or added stable to my fuel (for a second time).

It was probably a bad tank of gas, I'm glad (for now) that all is working correctly.

Thanks again for your help!