94 SLS back cyls spark, don't fire, smoke

**94 SLS** · 05-03-07 10:55 PM

I have a 94 SLS with 138,000 miles and a 4.6. To start it, the gas pedal has to be put down an inch or so. After a few seconds it starts and kind of putt putts. There is some black smoke that is noticeable at first. After a minute or two, and especially if you get on it, it pumps white smoke. The back four cylinders have spark to the spark plugs, but if each plug wire is pulled, there is no difference in the sound or performance. The 1,3,5,7 spark plugs are wet and white(new) when removed. The front 4 are dry and car stalls when plug wires are removed. At idle it is hard to rev up. It will barely drive and feels like it has a governor set at 10mph. I checked the injectors and the fuel pressure regulator for leakage three different times, but couldn't see any. The code is 034, the map sensor, which was just replaced by the previous owner, who also just replaced the intake gasket. I noticed a tiny bubble on the map sensor, not sure if this is ok or not. The code went to history for a couple of days, but did not improve performance. Little help please? Thanks.

**dkozloski** · 05-04-07 12:12 PM

Do you have the spark plug wires on the right cylinders?

**94 SLS** · 05-04-07 12:42 PM

Thank you for the reply. I have double checked that the wires are on the right coil twice, but because you said that, I am wondering if the last guy switched the coil packs. They are numbered starting at the passenger side, 6/7 4/1 8/3 5/2. I am looking in a manual and It looks like it should be 5/2 3/8 1/4 7/6. It looks like the coil pack is upside down. I will switch it and get back to you. Thank you.

**94 SLS** · 05-04-07 01:16 PM

After looking at it, it doesn't just switch and I was looking at the 4.9 coil pack picture (can't find one for 4.6). One thing I noticed when I pulled the plugs on the end of the coil pack is that all the prongs are there but 3 of the metal clips that attach to the prongs are missing. That looks of interest. I see that the firing order is 12734568 How does that relate to the coil positions?

**barryr** · 05-04-07 07:32 PM

I also have a 94 SLS, N* VIN Y, Firing order is 12734568. Coil positions starting from the left are Coil #1 6-7, Coil #2 4-1, Coil#3 8-3, Coil#4 2-5.
Even cylinders are in the front 2,4,6,8, left to right, rear is 1,3,5,7 left to right.
The coil mounting plate should have 2 wire prongs in the front for each coil pack. If all of this is correct on your car check the injector wiring from the fuel rail to the main wiring harness connector. May particular attention at the point where it bends around the water housing, I had several wires that fuzed together and caused the #1 & #3 injectors to remain open causing bellows of white smoke and horrible fuel economy.
Good Luck !!

**94 SLS** · 05-04-07 10:01 PM

Thanks for that info. I will look closely at the wiring from the fuel rail.

**94 SLS** · 06-06-07 12:06 PM

I checked the wiring in the fuel rail but it was all fine. One of the injectors was loose and dangling, so I popped it back in. (after starting didn't seem to help much, less fuel out the exhaust but still smokes and no power) I bought a noid light set and put the light in various injector clips, it didn't light up. Another thing, when the car is turned to the on position, I don't hear it energize. It doesn't make a sound to fill up the fuel rail. The fuel pump regulator and the injectors don't leak, but I don't hear any noise. Is it the fuel pump? The car barely moves in drive and to start it I have to put the pedal half way down. There are no codes and no service engine soon light. Any ideas?

**dkozloski** · 06-06-07 12:18 PM

What was the very last thing you did when this all started?

**94 SLS** · 06-06-07 01:02 PM

I bought a project car. The guy put a new intake on it as it was leaking oil. He couldn't get it started. I made that much progress( ha ha). I checked the fuel fuse and relay( I switched it with another), they seem to be fine. I listened in the gas tank and I could hear a motor for a couple of seconds. I started it and it ran better, idled by itself, but after a couple of minutes it smokes bad.

**94 SLS** · 06-06-07 04:06 PM

The noid light does not come on, so there is some problem between the computer and the injector, what are some of the things it could be?

**94 SLS** · 06-10-07 09:37 AM

The noid light does come on, I didn't know you had to try to start it to make it work. I put a new FPR on it, but haven't been able to start it, as now all plugs are wet. I'll keep me posted.