# 97 HB wont idle, black smoke



## Nice97 (Jan 13, 2007)

Ok well my 97 HB has been running very very bad for a few months now and the dealer cant figure it out. So in the morning i can drive about 5 min and it runs like a dream. After the 5 min its stats runnin really rich, and will blow black smoke. Well first we tried to pull the codes nothing, so we decided to do reg stuff like cap rotor wires and plugs but nothing. Next we did flow chats and still nothing. Well we went as far as taking the cat off the truck and sure enough we could see throught it nice and clean....... wtf then hmm well we left it off for the time being. The exhust is not kinda infront of the drivers rear tire and the rim is black it smokes so bad at times. Yea im gettin around 6 miles to the gallon atm with it running like it is so if anyone can think of something let me know. The mech at nissan is a good friend of mine and hes made calls to dealerships all over the south east with no luck on a cure. PLZ POST IF U HAVE AN IDEA =p thanks alot Dan.:lame:


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## golfer (Aug 21, 2006)

Strange that it's running that rich and the CEL isn't lit up like a Christmas tree. Makes me question the ECM.


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## Fred S (Aug 26, 2006)

golfer said:


> Strange that it's running that rich and the CEL isn't lit up like a Christmas tree. Makes me question the ECM.


It makes me question the dealership's "mechanic" who thought that spark plugs and wires would fix a fuel problem.

The fuel pressure regulator could be stuck closed, which would increase fuel pressure and make it run rich.

The MAF sensor could be kaput.

An injector could be stuck open.

Step 1 is to pull the spark plugs and see if they're all black or if just some or one of them are.

Also, what kind of engine have you got? V6 or 4 banger?

Fred


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## 88pathoffroad (Jun 6, 2004)

A bad or malfunctioning MAF, coolant temp sensor, TPS, or O2 sensor can all cause rich conditions. It could also be a clogged air filter.


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## Nice97 (Jan 13, 2007)

air filter is good all plugs look very bad black, its a 4 cycl, also the plugs and stuff was something i decided to do seein as it has 80k miles on it and nothing has been done other than oil and air filters. I guess what gets me as im guessin the trunk runs in default when its cold right? Well if this is the case when it decides its warn thats when it runs bad. Like this morning it was cold and i got all the way to work just fine about a 5 mile drive. Got ready to come home and it was a good bit warmer out the truck ran good for a few min then dead again. Also i forgot to add this yesterday sometimes if i hold the clutch in and full throttle it it will clear up and run fune for a few min.


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## golfer (Aug 21, 2006)

Certainly could be the coolant temp sensor.


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## Retired 461 (Jan 11, 2007)

What does the temp read when it runs poorly?


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## Fred S (Aug 26, 2006)

Retired 461 said:


> What does the temp read when it runs poorly?


If it's a V6 that won't tell you anything. The V6 has two sensors, one for the gauge and one for the computer.


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