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

[meandad]

yup 145 +_5 on all cylinders, all that type of stuff I checked first because it didn't cost anything. If you look a few posts back, I put up a complete recap of everything that was done. It's really extensive. I was going to start taking the upper intake off tomorrow to start checking the injectors, but I'm going to rest up instead. I spent about 5 hours yesterday putting new motor mounts in my Dakota truck. I figured it to be about an hour. What a nightmare.

[sly]

yeah... I looked... I didn't see that so I asked. I just looked again and saw it. damn my eyes.

the only thing left is gaskets that I can think of. If there's a very small coolant leak into the intake, it could cause that, but it's typically at the EGR spacer just behind the throttle body, not the intake to head gaskets (though that one does happen too). The EGR spacer is really easy to eliminate though. Take the long hose and drop it to the nipple on the driver side rear of the engine and then loop the short hose back up to the spacer to seal it up after blowing the coolant out of it. Added bonus... it's a freebie check and may solve the issue and only takes about 15 minutes to rig up.

[meandad]

No it's ok, I had the upper intake off before when I checked/replaced all the vacuum lines. I had the coolant lines looped together when I checked it the last time. Stupid me though, I forgot to check the injector harness before putting it back together. There was a mouse nest in there. I'm going to be really pissed if I check it this time and find something chewed through. I just fininshed my new super duper injector cleaner project though. I will put a picture of it up when I actually have it in operation. I'm really hoping the injectors will be the fix I need. Keep your fingers crossed.

[gadget73]

Ever checked it for slop in the timing chain? Pull the distributor cap off and put a breaker bar on the crank pulley. Rock the breaker bar back and forth and watch how far you have to move it before the rotor follows. It should be nearly immediate if the chain is tight, but if its sloppy you'll see it. Not all 86+ engines got the good timing set, and one of the hitching/bucking/other bs causes with the CFI engine is slop in the chain. I haven't worked on an 86+ that had the crap chain but I wouldn't be too surprised if a sloppy chain would cause the same problems in one of those. The crap timing set fails from age as much as anything else. it has plastic on the cam gear, and the plastic cracks off over time and creates a lot of slop in the chain.

[meandad]

Yeah I checked it, but I am going to double check it before I pull the upper manifold and start on the Injectors. Thanks for the reminder. It looked pretty good last time, but I'm going to get a second opinion from my brother this time just to be sure. The engine only has 65K on it. Have had this car in the family since it was new.

[meandad]

Well I went to check the timing chain. Cranked it one way, then the other and there was just about 1/4 " travel on the balancer before the rotor started to move. I think that's about 5 degrees. I mean all chains have to have some slop in them or you wouldn't be able to get them on. Whats everyone think good? Bad ? How bad is it to put a timing chain on this car. ?

[gadget73]

sounds like its getting sloppy. Chain isn't that bad. DO a water pump and add about an hour to it. Its not especially comfortable to do the job but its not really hard either.

[meandad]

I was messing around not wanting to start anything big, and found some wires stuck together in the harness going behind he engine. I believe it comes from the EGR and/or Ignition module. They weren't really shorted, but not quite right either. I taped them up temporarily, and disconnected the battery to reset the computer. Then I was also thinking about the Slymer coolant leak thing, and couldn't remember if I actually put the car on the road with the coolant lines looped off or was just running it in the driveway. Anyway I grabbed one of the hundreds of fuel line fittings that I bought in anticipation of doing my fuel lines, and used it to bypass the coolant lines to the intake. Took the car to work tonight, and it ran like crap for the first few miles. Then all of a sudden, it steadied out, and stopped bucking and jerking. It was like night and day. It might have been the computer adjusted itself after the harness fix, or it finished sucking what was left of the coolant in the manifold spacer. I will have to wait until the ride home to see if it starts off ok. I found when I got to work that I forgot to hook up /cap off the vacuum line I had the gauge hooked to also. I await the ride home with crossed fingers. I think I'm still going to do the fuel injectors though. I took a couple days off, and I went through all the trouble building the injector cleaner.

[meandad]

Nope no such luck, just a fluke I suppose. Car is just getting stranger and stranger. On to the injectors

[meandad]

Well I pretty sure the mystery is over. I saved the pain in the neck and expensive stuff for last, and it appears that's what it was. Yanked out the fuel rail, and all the injectors, put the first one in my spiffy new injector cleaner, and got nothing. Cranked the pressure up from 25 to 35, and still nothing. I'm scratching my head trying to figure out whats wrong with the cleaner I built. I took the first injector out and put in the new one I bought. It sprayed fine as did the other 7 from the car. Put the first one back in, and it still wouldn't spray. Took it out and put it one the ground while I went in the garage to get a fresh set of gloves. Came back and it had rolled into the pile of good ones so I had to test them all over again. Finally found it and put it back into the cleaner backwards and blew it out that way, and it sprayed normally after that. Didn't want to take a chance on it so I put the new one in instead. Put the car back together and it was 90% better. I still feel a little bobble in it, but I wouln't normally notice it if I wern't looking for it. I think I'm going to check the U joints and motor and transmission mounts since they propably took quite a beating from all the jerking the car was doing. Now I feel comfortable putting a set of new tires on it. I would like to thank all of those who gave me advice. This was definitely a learning experience. I have never had a problem kick my butt like this one.

[meandad]

I really have to fill the tank and double check the mileage. It looks like I just got about 127 miles on something less than 5 gallons of gas. I wasn't sure how much gas was in the tank so I put in $20. Gauge read 3/4 full. I went to work 4 days, and the needle dropped to about 5/8 tank. I put in another $20, and the gauge went to a low full.

[meandad]

Well I'm disappointed, It's still only 17 mpg around town. Still running ok though. Now I'm wondering if I should bring it to have the transmission checked. Hmmmmm

[mercurygm88]

17mpg in town is pretty good I get 12-15 in town, and 22-25 highway.

[johnunit]

Yeah 17mpg on any road with stop lights is pretty good for these cars. If you were getting that on the highway at a reasonable speed (ie. not cruising at 80mph) you might have a problem. In any sort of urban area though, 17mpg is probably above average for any panther chassis car. a 1990 Crown Vic is only rated for 15mpg city.

[sly]

my 88 gets between 13 and 15 city. so you're doin good.