| Author |
Message |
    
ErikS
| | Posted on Tuesday, March 05, 2002 - 10:55 pm: | 
|
My check engine light came on a week ago so I went to the dealer to get it cleared and they said it was a mass air flow sensor(has come on for the MAF several times) and also a no warm up fault. I know what the mass air flow sensor is but what causes a no warm up fault? They didn't feel like they needed to tell me other than I needed to replace the MAF. I have since done that(today) and the engine started right up but the second time it was started it idled really sluggish with the accelerator pressed and without it pressed(to rule out stepper motor) for a few minutes then ran fine. Also the check engine light came back on. I was told it takes a little while for the ECU to adjust for the new sensor, is this true and if so how long? |
gp (Garrett)
| | Posted on Wednesday, March 06, 2002 - 08:19 am: |
|
i have gotten the 'warm up' fault. replaced my thermostat and it took care of it. guessing that is what took care of it. it was obvious my thermostat was dead.....no heat. 15 min. and $10.
what year is your truck? |
ErikS
| | Posted on Wednesday, March 06, 2002 - 02:33 pm: |
|
It is a 96 sd with no display under the pass seat. I replaced my t-stat about 2 months ago because the engine wouldn't heat up enough for the heater to be hot. It was the stock replacement temp rated t-stat that I installed. No problems until just recently though. Any ideas |
gp (Garrett)
| | Posted on Wednesday, March 06, 2002 - 02:43 pm: |
|
its obd II then. the plug in is just above your gas pedal.
it takes a few cycles for the ECU to be clear of the old fault code.
i wouldn't have an idea more than what has happened to me.
call your dealer back and ask them what it all means. if not someone on one of these boards has to know.
good luck. |
Jon Williams (Jonw)
| | Posted on Wednesday, March 06, 2002 - 03:15 pm: |
|
Typically it takes 3 "run cycles" for OBD-II to clear a fault. The "no warm-up" fault can actually be resultant of a faulty MAF sensor. What happens is the MAF sends a faulty (or no signal at all) signal to the ECU that causes the fuel injection to run in "open loop" mode, which is what it runs in at cold start-up until the O2 sensors heat up and the ECU receives a warm signal from the coolant temp sensor. In the engine's wiring, the temp sensor and fuel temp sensor are in the same circuit as the MAF, and what usually happens is the faulty MAF sensor backs-up through the circuit and blocks or faults the signal of any other sensor in the circuit. Just be glad it showed the correct fault code, as sometimes it can indicate that a perfectly fine sensor is faulting when they're in a dependent circuit like they are on Rovers. |
ErikS
| | Posted on Wednesday, March 06, 2002 - 06:49 pm: |
|
So because I just replaced the MAF does that mean I possibly have a bad o2, temp, or fuel temp sensor that is causing the sluggish running when I go to start the engine after only 15-20 minutes of cool down time? |
Anonymous
| | Posted on Wednesday, March 06, 2002 - 08:25 pm: |
|
is there a way to check a MAF sensor out of the truck with a voltmeter/ohm meter. I've changed mine since the dealer said it needed changed and had them give me the old one. I would like to check it to see if it is in fact bad. Alot of cash for one so i don't want to throw it away if its not bad. I was kind of shocked that it went bad seeing as the truck only has about 45 k. |
Jon Williams (Jonw)
| | Posted on Thursday, March 07, 2002 - 08:19 am: |
|
Erik, I can see now that your truck is doing what mine was. I started by replacing the fuel temp sensor, and that cured the problem, but it never set a fault code. What you can do it use a multimeter and check the voltages of the coolant temp sensor and fuel temp sensor at cold and then at normal temp, and compare those values to the sensor voltages after the truck has been sitting for its 15-20 minutes. I tested my bad fuel temp sensor like that and found it was sticking "hot", so that's what was sending the faulty signal to the ECU (which apparently wasn't comparing the signals between the coolant sensor and fuel sensor; a proportional discrepency would set a fault code on any other vehicle). Of course, all this happened on my '95, so I didn't have OBD-II to guess for me. It gets expensive when you just start replacing sensors... |
ErikS
| | Posted on Thursday, March 07, 2002 - 07:58 pm: |
|
Ok, where is the fuel temp sensor and coolant temp sensor. I still haven't got around to getting a workshop manual. |
|
Closed: New threads not accepted on this page