: '94 SLS smoking bad

07-06-05, 02:23 PM
This '94 SLS smokes bad, it is a white smoke, and will start about 30 seconds after starting the engine, runs ok.
I pulled all the spark plugs wires and saw that the #4 and #8 spark plugs had oil all around them, I pulled all the plugs and turned it over 15 or 20 times, and looked down each hole, all looked the same, but #4 had a puddle on the piston head.
I pulled off that head,(left or front), and looked at underside of the head, the color on the #4 & #8 was a little darker black than the other 2, the cylinders looked good, the headgasket looked ok.
I took the head to a head shop, and they said it was warped to .004, and needed other work, (unrelated to my problem), they also said there was no cracks, cost to do this head work is $178.
Does anybody think that the warpage could have caused the smoking?
I can not pull the engine out to get to the other head, and I can't afford to pay the cost to have it pulled out for me.

If I pay the cost for the head work and do the labor to re-assemble, and it still smokes, I will be very tense.

thanks for any input.

07-06-05, 06:44 PM
Have you checked for a stuck open injector?

07-06-05, 10:39 PM
It sounds like all that is wrong is an injector stuck open....or possibly the fuel pressure regulator is leaking inside the intake manifold. Nothing you describe indicates a problem of anysort with the cylinder head.

07-07-05, 12:17 PM
wow, that is good to know, I will be putting the head back on, all that goes with that big job, and I will check the injectors.
Is there a easy way to check them? I can check them with a meter, would the stuck injector shoot fuel all the time with the key on?

07-07-05, 12:37 PM
Hey folks, since Reactor has the head off, wouldn't it be a good idea to replace the valve seals? How long do they last?
What else would you do after all the trouble of removing the head?

07-07-05, 07:56 PM
I don't know about valve seals but if the head is off, I'd timesert it before putting it back on to avoid having to do it again. I have never heard of problems with the valve seals.

To check for a stuck open injector, put a fuel pressure guage on the service port on the fuel rail and turn the key on to pressurize the system. Check the fuel pressure and then turn it off. If it does not hold pressure then pull the fuel rail with the injectors attatched and turn the key on again. This time watch the injector tips to see if any are leaking or spraying.

07-08-05, 08:46 AM
Thanks, for the info.
What is the correct Torque for the head bolts? 50 Ft Lbs?

07-11-05, 08:52 AM
I tested the injectors, they seem to be ok, but when removing the head I bumped them around a little, this may have unstuck the stuck one.
The problem may have been with the wiring to the injectors, I inspected the wires from the injectors to the big connector, and 4 or 5 of them had insulation missing, exposing the wire to touching the trans. case grounding them, this could have caused the injectors to fire, weather they were suppose to or not.
if the injectors are switched by grounding.

07-11-05, 09:57 AM
The wiring was probably your problem all along. Very rich conditions will produce white smoke.
Well now you know how to remove a head. Maybe you should timesert it as suggested while you can? Anyone?

07-11-05, 11:03 AM
I'd timesert it, for sure...easy insurance against future problems, at least with that bank.

Travis Goode
07-13-05, 08:10 PM
I also have a 94 SLS with 228K with a white smoke glitch. I recently purchased it from an individual. He had it for 4 years & most all the maintenance was done at the dealer. He bought it with 144K on it. He told me about the morning white smoke (smells normal - no sweet smell). Haven't made any of the above recommended checks yet. After starting in the morning everything is fine for about 3 - 5 minutes then the heavy white smoke starts up. Prior to the white smoke it sounds like the engine takes on a load (similar to ac kicking on) then the smoke kicks in for about 5 minutes & then it starts to go away & soon after there is just a wisp out the tail pipe. Any additional suggestions on what the problem might be? Thanks.

07-13-05, 11:15 PM
It may be the fuel pressure regulator leaking fuel into the intake manifold and it takes awhile after a start to clear it out.

The 94 has the large plenum style intake manifold. The silver top cover is actually the functional cover of the intake manifold. Take the perimeter row of screws out of the cover (leave the center, recessed screws in place) and lift the cover off. The fuel pressure regulator is the small canister shaped device near the throttle body end. Turn on the key to pressurize the fuel system (do NOT start, just turn the key to on) and watch the vacuum nipple for any sign of fuel leakage. There should be none. The FPR is actually inside the intake in this setup so any leaking fuel drops to the bottom of the intake and takes awhile to be pulled out as the engine runs.

Travis Goode
07-14-05, 07:29 AM
Thanks for the additional info. Planning on checking it out over this weekend.

Travis Goode
07-16-05, 09:55 PM
I pulled the top cover off yesterday & it has a bit of moisture/sweat looking farnish color through out (gas). I didn't notice a line connected to the FPR nipple (?). I cleaned off the top surface of the FPR & turned the key to the on position & noticed a little/slight wetness below the nipple, but nothing coming out of the nipple end. The fuel rack is very difficult to unlock from the clips (didn't want to break the plastic). Going to attempt the rack injector removal again tomorrow to see if the injectors are leaking. Is it better to replace a bad injector or rebuild (if possible). $63.00 a piece at Autozone. Appreciate any advice on this situation. Thanks.

Travis Goode
07-17-05, 07:17 PM
Trying to remove the fuel rail to check injectors/FPR for leakage & the right front corner will not come loose at what looks like a coil with wires coming out of it. All other areas are free. Using this site to determine the white smoke problem. Thanks for any help.

07-17-05, 10:50 PM
Sounds like the fuel pressure regulator from the description of the wetness at the vacuum nipple.

The fuel rail should pull upwards to allow replacement of the FPR. There is an o-ring seal around the FPR and the fuel return line. Possibly the fuel return line is holding the FPR in position.

07-17-05, 11:33 PM
Hi bbob,
I saw a older thread you answered about aligning the cams.
I did not remove the engine and all the sprockets and chains are on and good except the one I removed to take the head off. Can I put the crank at #1 TDC and put the Exhaust cam mark "FE" up and the intake cam mark "FI" up and slip the chain back on?
thanks for your help.

07-17-05, 11:44 PM
No...see your other post.

07-18-05, 09:37 AM
I have another '94 SLS 4.6L I drive everyday, could I set it to a reference, like #1 TDC and look at it's cam sprockets, then set to one I'm working on to the same position?

07-18-05, 10:22 AM
I read the other post.

Travis Goode
07-18-05, 07:22 PM
OK I got the rail disconnected & removed the FPR. Took some extra wiggling & slight prying with a screwdriver to dislodge the right front corner.

More questions:

The FPR had dampness on top, but nothing out of the nipple (when power was applied). There was no hose connected to the nipple nor evidence of one broken off, etc...should there be a hose connected to the nipple? If so, where does the other end connect?

How do I test the injectors? The fuel source was disconnected from the rigid tube when I removed the rail & there is little clearance to inspect for leakage when re-attached to the fuel sourcs? Thanks.

07-18-05, 09:32 PM
There is no vacuum hose on the FPR vacuum nipple on a 94 as it is inside the manifold and no vacuum hose is needed.

You will need to cobble up a way to hook the fuel pressure to the fuel rail to see if any of the injectors are leaking...or...put it back together, install the manifold top cover, remove the 4 screws holding the manifold to the cylinder heads, lift the manifold up and then power up the fuel pump with the manifold separated from the cylinder heads. With the manifold raised you can see the injector tips in each of the intake ports of the manifold.

Travis Goode
07-20-05, 12:32 PM
Update - Replaced the FPR & checked/cleaned the injectors (Berryman spray). No real noticable leakage (with power on). #8 had some slight dampness. Put it all back together, started it up & the white smoke appeared after about 5 minutes of running. Let it run for about 10 minutes & turned it off (the smoke remained, but had let up some). Let it cool off & checked the front 4 plugs. All looked ok,except # 8 was very black. Picked up some new plugs & changed the front 4. Started it up with no smoke. Did a couple of restarts (waiting about 15 minutes between starts) & the smoke was gone. Changing out the back 4 plugs this evening & hope the problem has gone. Suspect # 8 injector is acting up & will replace if the problem returns. Same goes for whatever is discovered with the back 4, if the plug shows any signs of excessive black appearance. Thanks for all the help & will advise any additional signs of smoke.

08-03-05, 01:44 PM
I got my '94 back together, fixed the injector wiring and checked the injectors,then started it last weekend, still smokes like a James Bond car, I guess the problem is the right head, (the one near the fire wall), the only way to get that one off is to remove the engine, right?

08-03-05, 02:28 PM
That is the prefered way.

08-07-05, 05:51 PM
I did all the tests, (a)compression tests;
cylinder 1 - 167psi
2 - 160
3 - 165
4 - 153
5 - 180
6 - 160
7 - 170
8 - 160
(b)I did the leak down test with a homemade adaptor using a old sparkplug, pressurized each cylinder to about 120psi for 5 min. each, no bubbles.

(c)I pressurized the cooling system to about 20 psi for 24 hours, and turn the engine over, no coolent was visible.

(d)I watched the injectors fire will the engine was turning over using the starter, all fired fuel in sequence, but all seem to fire a heavy load of fuel, I don't know what a normal amount looks like, but none of them were stuck.

The head near the front of the car has been worked and re-installed, the back head seems to be in good shape from these tests.

What can I do now? I do not know what the problem is.

This car smokes so bad and runs a little rough, the smoke is white ish, and is so thick you can not see past the rear bumper for 20 ft up into the air.

Thanks guys, I'm on a tight budget and I would like to get this car fixed.


08-07-05, 06:40 PM
(b)I did the leak down test with a homemade adaptor using a old sparkplug, pressurized each cylinder to about 120psi for 5 min. each, no bubbles.
Did the cylinders hold pressure? Sounds like you have eliminated the head gaskets. What does the smoke smell like? Oil or fuel? If it is fuel, and that thick, you should be able to ignite it.

08-07-05, 10:14 PM
Yes the cylinders held the pressure.
It has a very funny smell, not like the oil smell, not sure if that is a fuel smell.
I do not want to ignite it to find out, with that much smoke, it could kill me.

08-07-05, 10:17 PM
If the vacuum on the fuel regulator was missing causing the fuel regulator to keep the pressure to high, so the injectors are injecting way to much with each pulse or Could it be a fuel regulator itself?

08-07-05, 10:30 PM
The FPR on the '93/'94 is inside the intake manifold and is subjected to manifold vacuum so vacuum cannot be missing.

08-08-05, 08:57 AM
Any suggestions


08-08-05, 11:12 AM
How about the fuel rail? Any leaks there? Check it the same way as the FPR. You really need to figure out what is causing the smoke, fuel, oil or coolant, which should be evident by the smell.

08-08-05, 01:45 PM
I have a couple of questions, sorry if they were answered somewhere.

What's the fuel mileage...either instant or actual.

Is it loosing coolant?

How do the plugs look?

Even though it has good compression the oil rings may be stuck. There is a solvent procedure to clean them. Have you considered that.

08-08-05, 02:44 PM
I will check it out, I did not notice any leaks on the rail, when I took the cover off. The FPR and the rail area looked damp to me with a brown varnish look, but nothing dripping or anything.

I know what burning oil smells like and this smell is different, I don't know if it is coolant or fuel. I will check the smell and note it with more detail.

Fuel mileage is consistant at about 20 mpg, city, which it has done for a long time.

Not loosing any coolant, I don't have to top off, and no check coolant level indicators.

plugs look normal, a little black, nothing that jumps out at you.

It could be using oil, it has a pretty good oil leak around the pan, but it was not smoking, the smoking started all of a sudden while driving down the road, one second all was fine, the next, smoke, ( but it still ran ok, just a little rough).

Can you tell me more about the "solvent procedure" to clean the oil rings?


08-08-05, 04:04 PM
There are old threads that go into detail. Pull the plugs, pour a solvent into each cylinder, let it set for several hours, vacuum out, change oil to get what ran down, run engine. It is an authorized Cadillac service.

08-08-05, 10:20 PM
I will check it out, I did not notice any leaks on the rail, when I took the cover off. The FPR and the rail area looked damp to me with a brown varnish look, but nothing dripping or anything.

That is normal. What you are seeing is oil residue from crank case gasses that are drawn in through the PCV.

08-09-05, 05:56 PM
If the vacuum is from the intake manifold itself, would a missing or broke off gromet at the end of one of the injectors be a problem?

I looked at the injectors again and found one of those green rubber gromets that are at the end of the injectors was missing half, like it had broke off, so that injector when placed in the spot in the intake case was not sealed around it in the case.
would this be a issue?


08-10-05, 09:34 AM
:bonkers: can anyone tell me if the bad grommet would cause my problem?

08-10-05, 10:23 AM
It would be a vacuum leak but shoulsn't be causing any other problem.

08-10-05, 11:15 AM
Do you think with a vacuum leak in the intake, the FPR would be affected, due to it needing the vacuum to control the pressure correctly?

08-10-05, 08:41 PM
I don't think it would effect the fpr. Replace it and see, but I think it's a minor problem.

08-13-05, 06:43 PM
I did more troubleshooting today, I checked the fuel pressure, it is fine, I plugged the coolent going through the throttle body, thinking maybe coolent was getting in there.
started the car, still smoke.

I took the cover off the intake and noticed the bottom of the intake was a little lake of fuel, the intake should have nothing but air in there, right?

So where did the fuel come from? I got all that fuel out of the intake, checked the injectors for proper setting in the rail, and checked the rail, and checked the fpr to see if it was seated good.

Ran the car again, this time there was no smoke at all, for about 3 min. then it started again, but not as heavy.

I removed the cover again, expecting fuel in the intake, but it was about the same as it was after I cleaned it, I re-assembled it, and started it again, it ran smoke free for about 3 min.

The smoke is for sure caused by fuel.

I am letting the car sit there with the fuel pressure, (about 45psi), on it, and see if it drops over time.

Can the fuel leak only be pressent when the car is running, (injectors firing)?
I would not see the leak on the pressure gage, while running, due to the fuel pump.

Is it possible for a injector to be cracked and only leak to the inside of the intake when it is firing?

I plan on manually firing each injector while it is under the fuel pressure to see if it leaks, would this be a good test?

thanks for the help

08-13-05, 07:00 PM
You should be able to spot the leak by simply turning the key on with the intake cover off but DO NOT crank the engine. Turning the key on will pressurize the fuel system. Any leak should become apparent immediately if it is a big leak. Even if it is a very small leak it should become evident after a few minutes.

08-14-05, 09:18 AM
Well, 7 of the 8 injectors seem to show a wetness down the side of them, the 1 is totally dry, but no outright drips,

I removed the FRP, what would be the a good way to test it for proper operation?
(apply pressure to the inlet, and put a vacuum on the vacuum port and see if the flow to the outlet reduces?)

08-14-05, 12:19 PM
Don't pressurize the system with the FPR off or you'll have a fuel fountain. A bad FPR should make itself evident by simply turning the key on. If there is a bad daiphram in it, it should leak out of the nipple.

Maybe the injector "O" rings are bad or not seated properly. A stuck open injector is a possibilty but that would not lead to a puddle or "lake" in the intake manifold. That has to be coming from the fuel rail somewhere. Maybe it is a very slow leak. Remember, the fuel pump only runs for a few seconds if the engine is not cranked and then shuts off til it is cranked so pressure will drop off if there is a leak. Put the guage back on it and watch it. If it drops down, repressurize it again and again each time it drops. Maybe it will take several times to spot the leak. Any fuel on the oustide of the injector would be suspect as it should be perfectly dry.

08-14-05, 05:58 PM
I will run some more checks.


08-15-05, 12:37 PM
ok, today I checked each injector by putting about 75psi of nitrogyn in and actuating the injector, all worked but 1, it would turn on & off, but when it was off it still leaked a little nitrogyn.

I exercised it several times, then it started to work fine.

All the O-rings at the tops of the injectors where they attach to the fuel rail seem to have very small leaks, ( a wettness on the sides of the injectors).

On the FPR I tried to put pressure on the intake, about 50 psi to 75 psi, and see if I got flow at the outlet, there was no flow, I applied a vacuum, about 1 or 2 torr, and tested for flow or lack of, there was no change, this confused me.

I thought that with no vacuum the FPR would be open and pressure/flow should go right throw, and with vacuum the FPR would be closed and the flow would stop.

It flowed fuel when it was in the car, so I think it is fine, but not sure why my test did not work.

I'm going to replace the O-rings, and put it back together and see what happens

any suggestions?


08-16-05, 09:08 PM
Not sure what you mean "It flowed fuel when it was in the car". There is a vacuum diaphram across the inside of the FPR with fuel pressure on one side and engine vacuum on the other and never the twain shall meet. There should be NO fuel leaking out of the nipple.

08-17-05, 06:21 PM
I'm not sure if I suggested this before, have you checked the wiring harness into the intake manifold? There have been a few that have the insulation falling off the wires, causing shorts and strange operation. Take the plastic tubing off and see how the wires look.