Engine Miss

[smudvapor]

I have an 88 2.9. I start the truck and it runs very rough like it has a very bad miss. It also blows smoke. After I drive it a few miles it just smooths out and runs great. If it sits and idles for a while it will just all of a sudden start idling rough again. I have checked the wires, plugs, coil, map, relays, tps, cap, fuel, ground wires. I don't know what else to do. Any suggestions?

 

[cowboy63645]

Have you tried cleaning the throttle body and the MAF? Also, check the oxygen sensor, had one go out on mine and it ran like crap until I replaced it

 

[smudvapor]

I cleaned the throttle body. I don't think I have a maf do I?

 

[chazzone]

I cleaned the throttle body. I don't think I have a maf do I?

No the '88 doesn't have a MAF.

It'd be a good idea to check all the usual suspects (O2 sensor, MAP sensor, TPS, etc)

But if it's blowing black smoke (you didn't say) it's running rich. May be a stuck injector. I'd also check the Fuel Pressure Regulator and the vacuum line running to it, especially if you can do it when it's running rough.

 

[rangerguy351]

hook a fuel pressure gauge up to the rail and shut it off it should hold 29-40 psi beings its older if it don't then you got a injector sticking open. to find witch one pull the spark plugs out and see what one is black/rich. also when its running pull the front water temp sensor off and see if it smooths out. i just had mine doing that its just behind the thermostat housing . also the oxy sensor will do the same thing. any thing that will tell the computer hey we need more fuel

 

[rangerguy351]

o also i had a 4cylinder do something similar and it had a broken prong in the computer making it come up to high idle like it started cold that made my exhaust glow orange from to much fuel in the exhaust. change computer and it was fixed

 

[IMenriched]

are you loosing coolant?

 

[kimcrwbr1]

did you clean the IAT intake air temp sensor

 

[smudvapor]

I am not losing coolant. Where is the IAT?

 

[kimcrwbr1]

Not sure where but you have the AIT air charge temp 2 wires light grn/purple and blk/wht

 

[IMenriched]

How about a if a compression check...has that been done?

 

[smudvapor]

It runs like crap until I drive it a mile or two, then it runs fine, all day and all night if I want. After I have been stopped for a few minutes idling it will run like crap again. White smoke, really bad miss. If I drive it again then after a mile or so it runs great again. This thing is driving me crazy. I checked the computer for codes and it says all is well. I checked all of the usuall suspects and so far nothing.

 

[low_five]

oh man, white smoke is bad.

 

[IMenriched]

It runs like crap until I drive it a mile or two, then it runs fine, all day and all night if I want. After I have been stopped for a few minutes idling it will run like crap again. White smoke, really bad miss. If I drive it again then after a mile or so it runs great again. This thing is driving me crazy. I checked the computer for codes and it says all is well. I checked all of the usuall suspects and so far nothing.

Is this a auto automatic tranny??

If yes....then check to see if the tranny fluid is low, & prolly is.... if you're not low on coolant, (double check coolant level).

if the tranny fluid is low....then you might have a bad vacuum shift modulator on the tranny.

My guess is that you are really loosing coolant....slightly....and have a bad head...or outside shot of a just a bad head gasket.

 

[smudvapor]

5 speed tranny. The smoke is not thick, there is just a little. There is not coolant loss. I really think it is a sensor or electrical. It will idle fine and then just change and run really rough like it has a bad miss.