I thought at first that i ran the fuel too low and clogged up the fuel filter with crap from the tank. I've pulled it off and checked it and it seems fine. now everything i read is somewhat vague.. "MAP sensor, MAF sensor, TPS, Dirty Throttle body, EGR"..

it starts fine, but will not idle. even if i give it a little gas and hold it stable, the RPMs are erratic, up and down. if i give too much gas too fast, it bogs down. If i let off the gas, the idle drops to stall. If i "feather" the accelerator, i can get it up to higher RPMs, but it will sputter a bit and start dropping.

Please someone give me a more certain answer, I dont have the money to guess my way through this. Thanks

 

ok I measured the TPS with an ohmmeter. Pins A to B at rest measure 1.7k, wide open measures about 5.6k. Then from B to C measures just the opposite. at rest it measures 5.6k, wide open measures 1.7k. does this sound right? i started it without reconnecting the TPS. didnt seem to make much difference at all. still erratic up and down idle.

So i reconnected the TPS, DIS connected the MAP sensor and started it. it actually ran smooth and stable for a short while. even through reving. Short lived though. After reving, it started dropping the idle again and would go almost dead, then back up smooth, then back down again.. so on. Also the check engine light came on, which im sure it should with the map disconnected. no light with everything connected though. I assume that means it could still screw up as long as its within range of spec.

Im not sure how to test the MAP. Any ideas? this is my only transpo and i have very little money and a 7 yo to get around. so any help would be gretly ppreciated. thanks

 

ok, i was really hoping for some kind of answers. any direction would help. someone had to have seen this or had it happen before.

So I went out last night and just bought a MAP sensor. No luck. more searching today and found out how to short the ecm to read the codes. Initially there was a code for low MAP and a code for low TPS. but that came from me disconnecting them and starting the truck. So i reset the ECM, started the truck again.. same symptoms. then rechecked the codes. only code 12 now that i reset it.

So, someone please tell me, what causes these symptoms and does not throw a code? Im in desperate need of help here. its my only way to get me and my son around. And as i stated before, I dont have the money for a shop, or to just guess my way through a bunch of new parts i dont need.

Please help if you can. Thanks

 

The only advice i can offer is to be patient. (I know it sucks) But this is all free advice and if no one has responded it might be because they dont know and might be trying to find the answer for you. Im sure someone will give you an answer as soon as they can.

 

how are all your basic tune parts? like cap rotor wires plugs? are they in good working order? hows the fuel injector? is the spray pattern cone shaped? also did you check to see if any of the magnets in the distributor are cracked? if so it would cause a lot of problems.

 

Well, the wires look good, i havent checked the plugs. I just assumed that since this wasnt a gradual issue it must be something else. I drove to work just fine, when i went to leave to get home I barely made it. Not like a fouling plug or wire. Distributor may be an idea. I'll have to look at that. thank you.

And yes, im trying to be patient. I wasnt demanding answers. simply stating that i thought i would have more replies since it seems that so many people here seem to have a great deal of knowledge about this. Much more than me obviously.

Thanks for your responses

 

I was searching for an answer for my own problem and came across your and I hope I can save you some time and money. Check your fuel presure. After replacing all my plugs, cables, iac valve, spider coil(which is another to check, I had a clog in mine but that didn't fix it) and checking a million other things it finally came down to the fuel pump they are expensive, at least for my 97, but that did it. Come to find out these engines, the 4.3's seem to get pissy about a few psi below spec. Mine was putting out 52 and from one source it's supposed to be 70 to 90 but another said about 55. Either way that ended up being my fix and I had all of the same symptoms. Check your vac lines too. That can make em run rough. Hope it helps. My pump was 175 if I remember right but it was well worth it. Runs great now! Gl!

 

Well, I finally gave up and took it to the shop. $400 later, it was the fuel pump. Apparently not all the way dead. 18 lbs one minute, 0 the next. that certainly explains the erratic idle.

So, thank you all for your help. and i hope this helps someone else to save a little money before buying all the little parts and guessing.

 

I am currently having similar problems. My 2001 balzer idles low, but once the engine is over say 800rpm and over it mostly works fine. The engine idles rough again when I come up any small hill can any one tell me if it could be the MAF. I have already c/o the TPS. So I think the only other thing would be the MAF