# 98 Frontier 5spd 4cyl Stalls then restarts when warm



## ovtim (Feb 8, 2011)

HI All, I am sure you have heard something like this before as have I but this one has kicked my butt. 98 Frontier 150k well maintained good running truck when cold ....when warm dies then will restart fine can even cycle the ignition when at speed and drop the clutch and it will pick right back up as if nothing happened. (happens so often when warm it is not really driveable) If I dont cycle the ignition It wont start back up. The only code I ever got was EGR and O2 Primary sensor. Took EGR out of the loop and no more codes. Checked everything I could think of. Plugs wires cap rotor. Checked fuel pressure. Compression. No indication of running rich or lean. It still dies when warm then restarts immediately. Things I have been think about replacing are MAF senesor, Temp Sensor, Distributor. In the past I know that coils can cause simular problems but it has been my experiance the they usually wont restart immediatly. Any ideas or at least a good order in which to start throwing parts at this truck. Thank you Tim


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## azrocketman (Oct 5, 2005)

I would not replace the MAF sensor yet. I'd clean it, either with solvents they sell specifically for cleaning the MAF or using electronics contact cleaner. Be careful, becuse the MAF wire is relatively delicate.

That is the first thing I'd look at. Try it and write back.

Steve


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## ovtim (Feb 8, 2011)

*MAF Sensor*

Thank you for the reply Steve I did forget to mention that I have removed and cleaned the MAF sensor, with sensor cleaner. When I pulled it out I noticed some moisture leaking from the sensor but I am not sure if it was from attempts to clean the throttle body. The sensor visually looked ok. I have been somewhat leary of the MAF sensor since then but I wasn't sure if it could cause a problem like mine. I thought it may just cause the motor to run rich if it was bad also no check engine light. Any thoughts. I wish I was still in Tucson (my home town) I retired from the Fire Service there in 2000 an moved to windy and cold Kansas.


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## azrocketman (Oct 5, 2005)

ovtim said:


> Thank you for the reply Steve I did forget to mention that I have removed and cleaned the MAF sensor, with sensor cleaner. When I pulled it out I noticed some moisture leaking from the sensor but I am not sure if it was from attempts to clean the throttle body. The sensor visually looked ok. I have been somewhat leary of the MAF sensor since then but I wasn't sure if it could cause a problem like mine. I thought it may just cause the motor to run rich if it was bad also no check engine light. Any thoughts. I wish I was still in Tucson (my home town) I retired from the Fire Service there in 2000 an moved to windy and cold Kansas.


You could disconnect the sensor for troubleshooting. Doing so will cause the OBD II to sense a fault and it will light the SES light. The reason to do so is that it forces the computer to run in a backup mode (the engine will compute the amount of air it receives based on other engine sensors). If the problem goes away with the MAF disconnected that may be an indication of a bad MAF.

An alternative to just replacing parts is to find someone with a more sophisticated OBD II scanner that can look at engine "trims" and even "live" data. That information can be helpful in locating the system/component responsible fotr the shutdowns.

Steve


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## smj999smj (Jan 1, 2006)

I would be looking at the base idle speed adjustment and the IACV-AAC valve operation. This valve maintains base idle and compensates for loads, such as P/S and A/C, and also controls fast idle for start-up. If the base idle is improperly adjusted to spec., then the IACV-AAC valve doesn't operate properly.


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## ovtim (Feb 8, 2011)

*MAF?*

Well here's what else I know. I ran the truck warmed it up took a long time because it is really cold here and sure enough it died. I checked it a couple of times and it didn't matter weather or not it was at idle or at a couple thousand rpms. I then disconnected the MAF sensor wires and started it up. It ran but did not excelerate very well. Of course I got the check engine lite. The truck did not die. Ran rough but continued to run. The codes were odd. 1400 EGR solanoid and two 100 codes which are O2 sensors. Never the MAF code. Anyway I reconnected the MAF sensor and truck ran pretty good at first then started to die. I did now notice that it was running very rich. Black smoke and raw fuel smell. Would not stay running for very long. So before giving up think it would be worth changing out the MAF sensor or am I better off to admit defeat and take it to a shop. Anymore insite would be greatly appreciated. Thank you Tim


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## azrocketman (Oct 5, 2005)

ovtim said:


> Well here's what else I know. I ran the truck warmed it up took a long time because it is really cold here and sure enough it died. I checked it a couple of times and it didn't matter weather or not it was at idle or at a couple thousand rpms. I then disconnected the MAF sensor wires and started it up. It ran but did not excelerate very well. Of course I got the check engine lite. The truck did not die. Ran rough but continued to run. The codes were odd. 1400 EGR solanoid and two 100 codes which are O2 sensors. Never the MAF code. Anyway I reconnected the MAF sensor and truck ran pretty good at first then started to die. I did now notice that it was running very rich. Black smoke and raw fuel smell. Would not stay running for very long. So before giving up think it would be worth changing out the MAF sensor or am I better off to admit defeat and take it to a shop. Anymore insite would be greatly appreciated. Thank you Tim


I'd bet on the MAF sensor. Problem is that it is an expensive part to replace on a guess (RockAuto indicated a price over $200.00). If you have a shop with a good OBD II tester that can look at engine trims and live data then it might pay to let the shop have an hour with the truck. The O2 sensor codes may not be that odd since they were probably indicating mixture problems.

Steve


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