86 GM 5.0 with bad miss/sputtering/jerking. some Help would be nice

[meandad]

Did it start doing this all of a sudden or gradually over time?
If there are any junkyards near you I'd go nab a MAP sensor to try. Also you can test TPS function with a multimeter by probing the wires with it plugged in, key on. Black is ground, one should read 5 volts steady, and the other should vary from 1 to 4.5 volts or so as you open/close the throttle.
Of course double check the ECM ground at the battery terminal clamp too.

Yup checked the new TPS. it goes from about .9 to about 4.5 vdc. The problem started kind of all of a sudden, but did get worse over time. Now it's real bad. My next step is to put in a set of Ford Racing wires to replace the new cheapos I just installed. I figure they won't go to waste. If they don't help, I'll put them in my truck. I could try a junkyard MAP, but I'm afraid of the price. All the junkyards around here think their parts are made out of gold. I'll check though. Thanks for your input

[meandad]

What do you mean "water white"? did you mean "water clear" ? If your fuel supply could be questionable Id get it out and some fresh in. Ethanol gas is supposed to "go bad" much quicker...

Yeah, I meant water clear. Smells fresh too. I know because I got a kisser full of it when I was testing the fuel pressure. Everything was going fine. I finished, recapped the schrader valve but when I picked up the gauge the drain hose got caught on something and popped up in my face. Not very tasty

[86VickyLX]

Yup checked the new TPS. it goes from about .9 to about 4.5 vdc. The problem started kind of all of a sudden, but did get worse over time. Now it's real bad. My next step is to put in a set of Ford Racing wires to replace the new cheapos I just installed. I figure they won't go to waste. If they don't help, I'll put them in my truck. I could try a junkyard MAP, but I'm afraid of the price. All the junkyards around here think their parts are made out of gold. I'll check though. Thanks for your input

Firing order right?

[hypostang]

My part throttle stumble was a bad EGR valve , I removed and cleaned it but the problem persisted, It's disconnected now and though it throws a code, the car runs great , eventually I will replace it .

[merc91]

poping the hood in the dark with the engine running and light disconnected often puts a spark show out with the problems your describing. but that and egr are what will do that if your fuel pressure is not dipping to under 20-25psi which it shouldn't go under 35 anyways... and hold the pressure for a while after shutting the engine off. becuase if it drops like a stone, stuck open injector(s) which make it run like poo and soak your plug.

[meandad]

poping the hood in the dark with the engine running and light disconnected often puts a spark show out with the problems your describing. but that and egr are what will do that if your fuel pressure is not dipping to under 20-25psi which it shouldn't go under 35 anyways... and hold the pressure for a while after shutting the engine off. becuase if it drops like a stone, stuck open injector(s) which make it run like poo and soak your plug.

I tried the Spark in the dark routine, and it was putting on quite a show. I changed the wires, and didn't see anything after that but it seemed to run even crappier with the new wires. I'm going to change them again. I just ordered a set of new Ford racing wires. I still think the spark is weak. The fuel pressure was between 35 and 40, and held fine after shutting off the engine. I ran the car home on the turnpike, put it in the driveway, and pulled the plugs. All of them were wet with fuel. Not real wet, but wet. I put in new plugs just because I didn't like them. Also, I have a pretty complete machine shop at my house, so I made a blank plate for the EGR and capped it off. There was no change. The EGR sensor voltage also increments withing specs as vacuum is applied. I think the EGR is pretty much eliminated. Thank you for your reply.

[meandad]

Firing order right?

Yeah the firing order is the same as it was, I change one plug or wire at a time usually. It also matches the sticker on the car. I double checked it about a half dozen times. Just for fun, I might swap it over to the HO firing order when I get the new wires. Usually, I'm pretty sharp, but I never underestimate my capacity to do something stupid or miss something obvious. I do appreciate everyones input Thank You

[merc91]

i know you have checked the firing order to the point of goin nuts, but its what this sounds like if everything else us good. the spark show would cause it to run like crap... than putting on new wires but in the wrong order would make it worse of the same breed of problems. its the wet plugs that says firing order if your fuel pressure holds. are all of the plugs black and or wet? and do you get any backfiring up through the intake? and does it pop substancially harder under load?

[mercurygm88]

I had a similar problem in which the lopo firing order in both of my service manuals was incorrect. It should be cylinder #1 in the 12 o clock position then counterclockwise 1-5-4-2-6-3-7-8 both of my manuals showed cylinder #8 on the dizzy cap as being #1 pretty big mistake by them if u ask me.

[gadget73]

wet plugs sound like over-fueling. if its wet on all 8, either you have a pair of really really screwed up oxygen sensors, a constant stream of air being pumped into the heads from the air injection pump which is throwing off the reading the sensors get, or the MAP is bad or getting poor vacuum. If the air injection pump plumbing is screwed up and not diverting the pump to the cats or bypassing to atmosphere, it will just pump air into the heads, where it comes out in the exhaust ports. The O2 sensors show that as a lean mix, and fatten up the fuel mix to compensate. Might be worth pulling the belt off the AC/smog pump side and seeing if the car runs different. it should not.

[merc91]

running rich usually gives black dry powered plugs, to have a wet plug there would have to be an insane amount of gas im thinking, or lack of ignition. remember you need fuel, spark... annnd compression to combust your fuel. wrong firing order will spark when you dont have compression on the cylinder and your gunna have a wet plug. if they are all off a position... all wet plugs. but i would for sure do what gadget said and a massive vaccume leak would do this too, for some reason particularly 2 heft sized vac lines behind the upper intake into the firewall.

[meandad]

Ok I just put back the new distributor with new Ignition control module, and new pip sensor. Disconnected the battery for about 5 minutes to reset the computer. Car still runs like crap. Same bad miss. Would the described air pump malfuntion affect the car right away after a computer reset, or would I at least get a little bit of semi-noemal operation for a brief time? I also tested the vacuum at the MAP sensor and its still fine, about 22 lbs at Idle. Could it still be the stuff I just put on, and the computer needs time to learn? What is everyone's opinion. I know if I disconnect certain inputs like the MAP sensor, it gives an immediate change. How long does it take the computer to learn? I also triple checked the firing order, and all seems ok.

[merc91]

the computer already knows enough to instantly run fine. it will learn a few thinks to try to optimize performance and efficincy but nothing to noticible. a have built completely new motors with missmatched ford and aftermarket and and starts right up without popping or any rough running.

[meandad]

wet plugs sound like over-fueling. if its wet on all 8, either you have a pair of really really screwed up oxygen sensors, a constant stream of air being pumped into the heads from the air injection pump which is throwing off the reading the sensors get, or the MAP is bad or getting poor vacuum. If the air injection pump plumbing is screwed up and not diverting the pump to the cats or bypassing to atmosphere, it will just pump air into the heads, where it comes out in the exhaust ports. The O2 sensors show that as a lean mix, and fatten up the fuel mix to compensate. Might be worth pulling the belt off the AC/smog pump side and seeing if the car runs different. it should not.

Well it was a nice day today, so I took the belt off the Air Pump. No difference. I will take it to work tonight to run it around a bit
just to make sure. The Car knows I took the belt off too. Ran the codes, and it came up with a 94, and a 44 which are both
thermactor error codes. I ordered a Map sensor today as one of my last desperate acts. We will see. Thanks for your reply.

[gadget73]

yeah, the codes I'd expect, but it shouldn't run noticeably different otherwise if things are working as they should. Most of the smog equipment operates that way. It sets codes when missing, but you really shouldn't have any other indication that its not there. If it runs funny with the stuff present, then its probably screwed up.

other random thoughts, have you tried unhooking the green line to the EGR valve? It also shouldn't make any obvious difference in how the car runs but if the EVR gets sticky, it can yank the egr valve full open when its not supposed to be and that makes it run bad. Also, thinking about it merc91 has a good point about weak ignition causing the rich running problems too.