[raybie]

in the last few weeks i have had a miss that is getting worse. i started off just happening when i started the truck after is sat for some time, now it is pretty consistent. not head gasket because i'm getting black exhuast not white. it smells really rich and is getting about half my milage. i'm thinking it is an injector. anyone have any other thoughts or have had the same thing.

 

[Clifton]

Have you checked anything or are you hoping for a simple, it's this kinda answer. Did the check engine light come on? Did you pull a code? Does it do it at all rpm's and load or just idle? Also do you have an FSM or at least a Haynes and a DMV if so get busy. If it were me I'd check the coolant temp first. There's two sensors there, ones for the temp gauge. You can rule out the TPS, if you question the O2 sensor just unplug it and see if it cleans up, it WILL throw a code if you do this, just pull the efi fuse afterwords.

 

[hohardcastle]

Hey a buddy of mine had the same sort of problem with his. His truck started running really crapy and he went through a tank of gas in about two days and drove less than 20 miles. It ended up being that box that is right after the air cleaner. I am not sure what it is called but it is what regulates the air and how much comes in. I would say take it to a shop and they can test it to see if it is bad. Hope this helps

 

[Aaronn]

I say start with a tune up,then do what clifton said

 

[4X4buzzard]

Previous guy is talking about the MASS AIR FLOW sensor which does regluate fuel consumption to some extent. However best thing to do is code diagnosis. Find out if the computer can tell you exact problem first. If it is missing on the same stroke each time, your probably right it may be injector pluged. eeek or something worse like a valve <IMG SRC="smilies/crybaby2.gif" border="0"> . To check for burned valve pull the plug & it should show rusty colored porcelane (SP?) & element.

 

[crashinaz]

Had the same problem last year... Check the plug wires on the passenger side. The plastic retainers get brittle and break, letting the wires lay up against the EGR tube... Tube gets hot... Wire starts shorting to the tube... Motor runs like crap... Hope this does the trick. I've run across 3 other trucks local which suffered from the same problem. <IMG SRC="smilies/beer.gif" border="0">

 

[JCTOYS]

I had a problem like that with my truck twice. The first time it was a broken valve spring that caused two cylinders to miss. I fixed that and then six months later it started doing it again and this time it turned out to be the heads. Hope this helps.

 

[raybie]

i have check the plugs they look good. wires are new. compression test shows all holes from 160 to 165psi so that kind of rules out the valves. not lossing any water so no on the head gasket. no codes showing. did all that on my own and still no clue so i took it to the shop, he found that the throttle body was gummed up and cleaned it. couldn't find anything else. runs better but still when i start it, and it isn't evertime, it is missing and puking dark exhuast. clears up after a few minutes

 

[Clifton]

Originally posted by raybie:
<STRONG>i have check the plugs they look good. wires are new. compression test shows all holes from 160 to 165psi so that kind of rules out the valves. not lossing any water so no on the head gasket. no codes showing. did all that on my own and still no clue so i took it to the shop, he found that the throttle body was gummed up and cleaned it. couldn't find anything else. runs better but still when i start it, and it isn't evertime, it is missing and puking dark exhuast. clears up after a few minutes</STRONG>

You are running way to righ. A bad plug wire or bad valve will not cause that. A miss is one thing but if you are running rich enough to SEE black smoke coming out it's electrical. If it was a loose sensor wire it would show a code but if it was still getting a siganl, but way off it won't, you gotta check with a DVM. There's something telling the ecu to give alot of gas.

 

[Mean__Gene]

i had a similar prob. my mileage went to 10mpg at one point.. ended up being the O2 sensor... it can malfunction with out the ECU knowing it (no code) and cause the engine to run rich.
it was discussed on in this thread

[ 10-31-2001: Message edited by: Mean__Gene ]