Rough Idle, bucking...

[sleep7]

Rough Idle, bucking, exhaust stinks, anything under 4k doesnt want to accelerate. When its idle and I give it a rev, it hesitates, and you can hear it suck in air, then revs up. Dont know what my codes are because check engine light doesnt work. The wiring around the DIS module isnt the greatest either. Maybe I can post a pic of what it looks like.

This is on my 89, which had all the 60k maintanence down by Chris aka SHO--ripper before I got it. He also replaced the fuel pump before I got it. I was thinking possible vacuum leak?

 

[Yamaha V6]

Try the MAF for the bog / hesitation. It doesn't always trip a code, especially on Gen 1s.

 

[shospeed143]

Does it run better after 4k because if the Butter fly valves are open the car will run bad at idle up to 4k.

 

[sleep7]

It definatley seems too after 4k. The cars idle seems to be getting worse. The RPMs go between about 800 and 1100 RPM. Every once in a while when the car is cold it will stall. When I start moving I have to rev it up to about 2500 so the car doesnt bog or stall.

 

[BruceJEubanks]

Try the MAF for the bog / hesitation. It doesn't always trip a code, especially on Gen 1s.

I had this same problem then after a few years the CEL came on with codes of 181, 189, 542

 

[shospeed143]

Like i said before check your butter fly valves if they are open then the engine is gettting to much air at idle and it wont geve you a code for it. Also if you know how to pull cades try to pull them again once with the key on and then with the car running.

 

[Redskull]

Clean the MAF; I cleaned mine, and it fixed problems I didn't even know I had, most notebaly bucking when cold, low torque under 4k, and dying at WOT

alan

 

[sleep7]

I changed the MAF a while ago, didnt do a thing. Something else I noticed. Anything above secondaries gets plenty of white smoke out the back, which also happens below 4k, but not as much. I've also been burning oil. And watching my air/fuel ratio, I dont know how accurate the digital ones are, but when it doesnt want to accelerate, or idles rough it shows the car running way lean.

 

[dpsutphin]

This may sound overly simple, but I had the exact same symptoms in my 1990 SHO, minus the smoke and oil burning. Took me a month to figure it out. Changed plugs, wires, coil pack, MAF sensor, Cam position sensor, and a couple of other things. Then on a whim, I changed the fuel filter, which had just been changed about 5000 miles ago. Bingo, no more problem. I actually had to change it twice. Guess I had some trash in the tank. Anyway, it's a cheap part, and easy to replace. So it's worth a try.

 

[jaded93atx]

Without codes it is impossible to narrow it down to anything specific, the variables between mechanical or sensor related are almost endless- add the fact that it could be a combination of faults and your looking at a whole lot of time speculating, expensive parts throwing, and most likely negative results. If you indeed dont have a working CE light then get the codes pulled with a scanner, Auto zone will do it for free. Dont frustrate yourself and waste time and money guessing, it will be a losing, uphill battle.
Thats all I can really offer with the info provided just my humble opinion though.

 

[sleep7]

The fuel filter was the first thing I did.

See, I wasnt sure if I could get the codes checked without the CEL. I think I'll try that. I really didnt want to get into the dash and get that light working.

 

[40BelowSummer]

Yes you can check the codes without the check engine light via a scanner at someplace like Autozone or with a multimeter yourself.

 

[SHOtimer]

I changed the MAF a while ago, didnt do a thing. Something else I noticed. Anything above secondaries gets plenty of white smoke out the back, which also happens below 4k, but not as much. I've also been burning oil. And watching my air/fuel ratio, I dont know how accurate the digital ones are, but when it doesnt want to accelerate, or idles rough it shows the car running way lean.

That is a huge problem and can destroy your motor.

Doug

 

[jedhead]

I had a simular problem with my SHO many years ago. The plastic intake pipe between the MAF and throttle body was cracked. You may have a vacumn leak somewhere.

Bob

 

[CoolDenver]

http://www.shophoenixproject.com/eec/eec.htm
This site shows how to check codes.

 

[sleep7]

Dont know what my codes are because check engine light doesnt work.

Does Advanced Auto run codes for free?

 

[jaded93atx]

How 'bout them codes? Another source of a vacuum leak happens when the IAC sticks in the open position and allows air in past where the MAF can meter it, and will cause it to run lean. I never had a code for the IAC but mine would throw a 157, 172, and 176 code until I put in new Bosch O2s then just the 157, and kept making me think it was the MAF. It would also cause poor driveability and a CE light after letting off the pedal to slow down at highway speeds, other symptoms, more so when the car was warmed up,included an eratic/surging idle and stalling many times if I didnt feather the throttle at stops or any time I let off the throttle ie...exit ramps. Even though mine was a one piece design I was able to clean it (make sure you do it thouroughly and pay close attention to the shaft the plunger slides on, it collects alot of gunk that you may not notice at first and is the reason it will stick. Youll have to move the plunger back and forth and use a q tip with carb cleaner to get to it. I used the kind of carb cleaner that doesnt harm plastics. You can also test the IAC by "hot wiring" a 9 volt battery to the 2 terminals...youll be checking for the plunger to move when the leads are touched and will rule out a faulty solenoid, if its stuck youll at least feel it try to move.
Just a thought but those codes would really help us to help you.

 

[jaded93atx]

Im not sure about Advance...some of them might. What did you use to "see" that it was running lean, if it was a "real time" scanner that will also show your hard codes, but looking at your post again it sounds like you have a gauge hooked up.... Without a working CE light and the PITA involved of reconnecting the bulb you may want to invest the 15 or 20 bucks in a cheap or mediocre scanner, you only need one that reads Ford eec IV not OBD II so they should be pretty cheap.