missing and bucking some while cruising, good idle and good WOT???

Demented4.6 · May 21, 2004

Ok i have everything in my sig. Basically it runs great at idle and awesome at WOT but when it is cold it bucks while trying to take off and while cruising. also once warm it surges and sounds like it is missing through the exhaust while cruising only.. any clue

cardudeusa · May 21, 2004

Is there any codes? Try unplugging the O2 sensors drive it for a bit, if it goes away buy 2 new ones. I had the same problem on the my 87 GT, give that a shot.

Demented4.6 · May 22, 2004

no codes so far i'll try anything

cardudeusa · May 22, 2004

BOWTIEKILLER said:
no codes so far i'll try anything

Try unplugging the oxygen sensors like I said. I would think it could be TPS

dude5l · May 23, 2004

It could also be the MAF. Try "clocking" it. Start with the electonics at 12:00.

Demented4.6 · May 26, 2004

dude5l said:
It could also be the MAF. Try "clocking" it. Start with the electonics at 12:00.

Thats not a bad idea.. i have heard that a few times..

This problem has been around for a long time but i blew it off due to cam. but it is now getting worse to the point i dont want to drive the car anymore. I tried it while sitting still and if i rev the motor and hold it at any RPM you can hear a miss to it like a Hiccup you can also feel it in the motor like a jerk. any clues... i tried unplugging the O2's and no change. thanks guys

4dStang · May 27, 2004

Have you gone back to basics and looked at the cap, rotor and made sure the wires were all going to the right plugs. I had a miss problem that was kicken my butt and I went back to basics and found 3 plug wires switched. Recently I did a header change and changed wires at the same time to 45 degree ends and must have just fubared the wire install. Swapped the wires around and it doesn't miss anymore.

Next, I would look at the TPS. Especially if it is in the middle rpm range only that is causing problems. Change that biznitch out and then work towards TFI module (ignition module) next, then MAF (which I doubt if it is stock). I don't think 02's are the prob.

CB

Demented4.6 · May 27, 2004

I probably could do a cap and rotor and wires been a year or three, but i hardly ever drive the car.. what are some good wires?? i have MSD wires now

I doubt it has anything to do with the TPS. it could be doing it at idle but at idle it is lumpy and LOUD so its hard to tell.... it seems as the " miss " is less noticeable as it revs

5.0lpowerhouse · May 27, 2004

had a problem in my 89 where one of the wires hit my BBK Headers and caused all sorts of problems... I'd get Msd wires plus the heating shield they have for em' the BBK's have a tendency to get the underhood temps hot.. just something to look into

4dStang · May 27, 2004

I agree about the wires. I was coming back from the track and noticed that my car would miss when I would get it hotter, like on the freeway or heavy accelleration. Found out later that a plug boot had started to burn on my new headers and the spark was jumping to the header instead of the plug. Changed wires to 90 degree boots (had fat wire boots before) and routed all wires way far away from the headers and no more miss. I am using Mallory 8mm Stainless wires. But anything not at autozone is good! For wires: MSD, Ford Racing, Mallory, and a few others I cant think of now. Go to Summit or Jegs and look.

5.0lpowerhouse · May 27, 2004

this happen to me on monday of this week, my new wires and heat shield will be here tommorow.. for now it's doing ok with electrical tape until tommorow

BlackFox5.0 · May 27, 2004

Sounds exactly like a vacuum leak. I had the same exact problem. I couldn't figure it out, turns out it was the ear on my upper intake that the bolts goes through that was snapped off (I bought it like that but it was jb welded) So i just broke the rest of it off, clean it up, and had it welded (the right way) put good gaskets on the upper to lower, and the major skipping while cruising is gone....

I'd start with checking for vauum leaks before you end up spending big money. Spray around the intake with carn cleaner with the engine running, if the idle goes up you found where the leak is, but this method does not always work (such as in my case)

DropTopR · May 27, 2004

I had that problem after I did a head swap on my last car, and it would buck and miss at low rpm's and while cruising. Very irritating. Called around, and ended up getting some help from an editor of MM&FF. Said everytime he ran into that, it was an overly rich condition at part throttle. Dropped some fuel pressure, and it helped. Later, ended up reducing my part thottle fuel with my TwEECer. Might not be your problem, but it's worth a try.

Scott W · May 28, 2004

I'm having almost the same problem. lopes or surges under part throttle.

I'm replaced the distributor, cap, rotor, wires, coil, plugs, and I have a msd6al- so I don't think my problem is ignition related.

I[m going to check for a vacuum leak and check the tps.

What do you mean by 'clocking' the maf?

BlackFox5.0 · May 28, 2004

Scott W said:
What do you mean by 'clocking' the maf?

Just rotate the maf so instead of the electronics being at 12 o'clock try "clocking it" the the electronics are at say 3 o'clock

Demented4.6 · May 28, 2004

great stuff guys.. I am going to try some more things tomarrow and see if anything helps... Black Fox thanks for shooting me the idea of vac leak.. I have a vac guage in the car and while at idle it reads around 20-15 is this good?? I really don't think this is a ignition problem but i am going to replace upper to lower gasket and order some wires just in case.. also gonna screw with the MAF. thanks guys youve all been real helpful like always..
Marques

BlackFox5.0 · May 29, 2004

I engine was readin 15-20" of vacuum too, even after I fixed it, so thats not a very reliable way of checking....

90stangLX302 · May 29, 2004

My stang was having the same probem 2 or more months and i couldnt figure it out so i took it to th shop and they checked:Vacuum, fuel pressure, ecu, fuel pump and o2's. They couldn't figure it out. They said it was because i had my smog system off and it was causing the computer to be messed up. So i brought it home and put new wires, distributor, cap, and rotor. Didnt help. So i tried ne o2's. Still didnt help. I asked them if they checked the spark plugs and they said "No, but they are probably fine." I pulled the spark plugs out an 3 of them were completely fouled. They were gunked up to the point that i couldnt even see the electrode. Put new ones in and now it runs like a dream.

jrichker · May 29, 2004

Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

Matts89LX5.0 · May 29, 2004

i had a missing problem in my old stang. ended up being the roller rockers not being fully adjusted since they were studded. Are yours pedestal mounted or studded?

Matt

missing and bucking some while cruising, good idle and good WOT???

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