Ok for a longer history, please check this thread:
http://www.cadillacforums.com/forums/showthread.php?t=20733 (http://www.cadillacforums.com/forums/showthread.php?t=20733)

If you want just a summary here it is:

4.9L NON-Northstar, in a 93 Eldo

Missing in Cyls 3 and also 4. INTERMITTANT. Driving down the highway at 70mph+ it runs like a top -about 90% of the time. Sometimes in city driving, runs great (10% of the time). Sometimes feels like just ONE cylinder missing, other times, like both are missing.

When it's missing, the RPM needle jumps up and down spastically. The needle gets crazier the worse the engine is running.

NO CHECK ENGINE LIGHTS AND NO CODES until just recently! Related? I dunno, read on!

WHAT HAS BEEN REPLACED:

- All 8 Injectors with rebuilt from Linder Technical Services (highly recommended by this board, tested and guaranteed)

- All plug Wires

- All Spark Plugs

- Distributor and cap

Now, today I finally got a CEL so I got it read at Advance Auto and then also read the ECU thru the car itself (getting into the ECU thru the climate control buttons). Here's what I found:

P022 Open TPS Signal

P030 ISC RPM out of range

P052 PCM Memory Reset

P070 Intermittent TPS Signal

P091 PRNDL Switch Problem (transaxle range switch problem)

P098 High RPM P/N to D/R Shift Under ISC

I039 Loss of Road Sensing Suspension Data

I052 Keep Alive Memory Error

Advance had the P030 and the P070 (that's all they read).

I went ahead and bought a Throttle Position Sensor since that's bad, but I'm pretty sure it has nothing to do with the missing problem... OR DOES IT?

My questions:
WILL A NEW TPS FIX THE MISSING PROBLEM?
IF NOT, WHAT IS THE NEXT STEP?

Forgot to mention, in searching this website I've noticed people with similar problems that end up also having bad gas mileage.

My mileage has been averaging 15-18mpg in an almost 50/50 mix of highway/city driving.

When someone gets a dozen of codes I always suspect bad battery cables and connections.

CHANGE THE COIL. I'm not sure which coil setup your vehicle has, but a bad coil will do that EXACT same thing when it's going out. And it won't show up on any tests. Took me $500 and 3 months to track it down, since it "tested" ok. If it's sending current and voltage spikes, it'll also mess with the computer and other components--so computer/module/capacitor may have to be replaced next (especially if it develops no-start due to injectors not firing etc). You'll know it has some voltage problems if the climate control displays start acting funny when revved.

I would try that first and foremost, if the setup is anything similar to my 4.1L '82 Eldo.

Ok for a longer history, please check this thread:
http://www.cadillacforums.com/forums/showthread.php?t=20733 (http://www.cadillacforums.com/forums/showthread.php?t=20733)

If you want just a summary here it is:

4.9L NON-Northstar, in a 93 Eldo

Missing in Cyls 3 and also 4. INTERMITTANT. Driving down the highway at 70mph+ it runs like a top -about 90% of the time. Sometimes in city driving, runs great (10% of the time). Sometimes feels like just ONE cylinder missing, other times, like both are missing.

When it's missing, the RPM needle jumps up and down spastically. The needle gets crazier the worse the engine is running.

NO CHECK ENGINE LIGHTS AND NO CODES until just recently! Related? I dunno, read on!

WHAT HAS BEEN REPLACED:

- All 8 Injectors with rebuilt from Linder Technical Services (highly recommended by this board, tested and guaranteed)

- All plug Wires

- All Spark Plugs

- Distributor and cap

Now, today I finally got a CEL so I got it read at Advance Auto and then also read the ECU thru the car itself (getting into the ECU thru the climate control buttons). Here's what I found:

P022 Open TPS Signal

P030 ISC RPM out of range

P052 PCM Memory Reset

P070 Intermittent TPS Signal

P091 PRNDL Switch Problem (transaxle range switch problem)

P098 High RPM P/N to D/R Shift Under ISC

I039 Loss of Road Sensing Suspension Data

I052 Keep Alive Memory Error

Advance had the P030 and the P070 (that's all they read).

I went ahead and bought a Throttle Position Sensor since that's bad, but I'm pretty sure it has nothing to do with the missing problem... OR DOES IT?

My questions:
WILL A NEW TPS FIX THE MISSING PROBLEM?
IF NOT, WHAT IS THE NEXT STEP?




Reset the codes and see what ones pop back up. Sometimes codes pop up and then trigger other codes down the road. For instance my TPS shorted out. It caused a ISC Motor code and a few others, like MAP sensor. It quite shifting out of first gear and slipped at high rpms. It rumbled out black smoke and missed real bad and idled erratically. I would replace the TPS and then reset the codes and see what happens. They are not that expensive.

Blaze

Battery and cables and connections were already replaced (sorry I didn't mention that).

DrDave: I didn't think this car had a coil if it has a distributor? I'm not really familiar with it but I'll call around and see. :)

I replaced the TPS and reset the codes and none of the P0 codes came back except a new one.

P055 Closed Throttle Angle Out of Range [TPS]

The TPS can be turned a bit by loosening the screws so I assume I just need to readjust that...

Either way car still isn't running right, same problems.

HELP!!

Battery and cables and connections were already replaced (sorry I didn't mention that).

DrDave: I didn't think this car had a coil if it has a distributor? I'm not really familiar with it but I'll call around and see. :)

I replaced the TPS and reset the codes and none of the P0 codes came back except a new one.

P055 Closed Throttle Angle Out of Range [TPS]

The TPS can be turned a bit by loosening the screws so I assume I just need to readjust that...

Either way car still isn't running right, same problems.

HELP!!
The coil is in the distributor cap. It doesnt however have a coil-pack.

Blaze

So if they replaced the distributor cap, would they have replaced the coil, or should I confirm that with them?

So if they replaced the distributor cap, would they have replaced the coil, or should I confirm that with them?
They would have swapped the original coil to the new cap

Blaze

Do a compression test, ensure that you don't have a burned valve.

I don't care who rebuilt injectors, and how good their reputation is, get NEW ones, or ones that are VERY young (I got mine with <1000 miles on them). Never use rebuilt. That is a falacy in the name. They are not rebuilt, they are nothing more than cleaned. Nothing more. They cannot be dissassembled, only the inlet filter removed and resistance checked, cleaned and put back the filter. So you buy (for nearly as much as new ones!) someone elses junk injectors.

I have seen too many people get screwed on "rebuilt" injectors. The only way I would do that is if they give me in writing a lifetime warranty on them. Nothing less. And even then, I would be more than skeptical.....

As for the 4.1L, you can borrow the cap and rotor to test with, they are the same (as long as it is screw down and wire colors are the same, red/yellow or red/white, the wire colors are the wire turn direction of the coil)

Youbetcha77 can give you ideas on what bad wiring harnesses can do for you.

You might want to verify the ECM connectors (disable airbag before you try!!), fuseblock to dash and look for any other main connection points. If you suddenly see a lot of faults, it is VERY rare that one of them is a real problem. And TPS's can't cause a missfire.

N0DIH:

Wouldn't a burned valve ALWAYS cause a misfire? Could it be intermittant? And I mean intermittant as in within one "start" as well as sometimes an entire "start" it will either miss or not.

As for the rebuilds, the place I got them from came very highly recommended from many people on this board, and actually they did come with a very long warranty, I don't have it in front of me but it was at least 5 years. They had a list of things they did to them, and it was much more than cleaning... and they also were all flow tested and matched to within I think 5% flow. Either way, the exact same problem was happening before the replacement as after... so the chances of getting a bad injector AND putting it in the same cylinder AND having it act EXACTLY like the other one is a million-to-one IMO.

I have an update I'll post it in the next reply :)

You guys will love this one. I've pretty much confirmed it's ELECTRICAL. Here's why.

I had a bit of ... ummm... indigestion tonight (read: Gas). Wife didn't appreciate the Caddy smelling like a Pacer so I rolled down both windows. Cleared the air, put up both windows at the same time, and the instant that they were fully up (and I was still pushing the switches up)... the car STALLED!

WHOA... did that really happen? Got it started, drove a bit, just tapped BOTH window controls up, RPMs to "0", I let off, engine running again. I could repeat it.

Then I had a stop, turned it off, started it back up, now the car is on one of the "good" starts (ie. no missing!) so I tried the windows again... car KEPT RUNNING, the only thing was the lights dimmed pretty badly. But the RPMs didn't go to "0".

A while down the road, car started missing again, so I tried the windows and BAM, RPM's to "0".

So it seems when it's acting up, the window switches kill the engine. If it's running good, they only dim the lights.

Any ideas on where to start looking for this problem?

There is a service bulletin on moving the negative battery cable to a new location on the block. Mine was acting up and when I moved the cable it was fixed.

Blaze

My 92 Deville has similar problems but engine misses when anything is on lights windows, ect. just wondered if you had found a solution. thanks.

There is a ground stud right by the starter on the engine block. It is 8 x1.25 mm (standard M8) thread. If you can replace the stud (I found a 8 mm staud with nuts in a car parts store) , clean the connection, use new star washers AND put a jumper from the battery's negative post to this ground thru the exhaust manifold. I have done that while the car on jack stands, but it was not easy at all. Hoist would be great. I still believe the problem is electrical and my guess (lots of codes) probably was correct one.

That negative battery cable could be the problem. I would still check the coil though if nothing else works.