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1993 ETC, in Windsor, Ont.
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301 Posts
Discussion Starter #1 (Edited)
This is frustrating... I haven't been able to drive the car for a week.
I've had a few problems the last couple months- The MAP sensor wires were degraded in the manifold, and are now fixed. Next, hard starting after sitting was cured by a new injector o-ring on the front left injector.
It ran fine for a few HOURS.
Now, suddenly it "idles" (I use that term loosely) it will hunt between 1500/2000 rpm's and 0. Keeps pulsing around there, dying occasionaly . If it does occasionally settle at 900 for a few seconds, you can see smoke out of the exhaust and smell the distinctive "rich" sulpher smell from the cat. It will then start hunting again.
If you give it part throttle, (10% or so, enough to rev it up to 2500 rpms) it will rev and drop from 2500, then cut out completely until it hits ~1000, then rev back up again.
It's impossible to drive the car while it's swinging around a 2000 rpm range by itself!!!

I'm guessing it's something air/injector related, I don't know. I've had the manifold off 4 times in the last couple weeks for those other problems.
I'm going to check the o2 sensor data to see if one side is a lot richer than the other... may be a foobar injector.
Any suggestions????
(Oh, no codes BTW, and data from the TPS and MAP sensor are normal)
EDIT- o2 sensors are reading similar. I might have to drop it off at the (GASP) dealership!!!
 

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1997 SLS
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550 Posts
It's a long shot, but could it be your fuel pump? I had weird problems trying to start my sls, and sometimes it would run for awhile radically and then quit. Turned out to be a weak, but still barely functioning fuel pump. Are there any codes on the DIC?
Also, I did a throttle body cleaning and the idle was purrrfect afterwards.
 

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94 Eldorado, and a 99 ETC
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3,887 Posts
Poltergeist? lol

Ummm... do you hear a "ticking" noise from the ISC motor after you turn the engine off?

Does the brake pedal feel abnormally hard?
 

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1993 ETC, in Windsor, Ont.
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301 Posts
Discussion Starter #5 (Edited)
Thanks a lot for the replies so far guys.
It's far from being JUST the idle. I wish it was, otherwise I would actually be able to drive it to the dealership (looks like I may have to get it towed)
It does it at anything below 3500 or so rpms, it just jumps around like madness. It has a slightly less range of hunting the more you press the gas (while in neutral)... the more throttle you give it, the less it will hunt, but it will do it quicker as well. In basic mechanic theory, all this usually means vacuum leak... but there are so many other damn systems on the car that could be contributing.

Also, the higher the throttle was when you let off, the more likely it will simply die when you let it off.
 

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1997 SLS
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550 Posts
Sidebar: Thanks Ranger for the tips on a leaky FPR. I changed mine (very easy) and the hard starting problem when hot went away immediately. I was astonished how expensive the part was though - $57.
 

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1993 ETC, in Windsor, Ont.
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301 Posts
Discussion Starter #8
Doesn't leak- no fuel leakage from the FPR.
I don't know about the ISC motor... from the other thread, it seems that it wouldn't be causing the speed hunting/pulsing when you are on the throttle, and it still does it up to almost 1/2 throttle.

Come to think of it, it started the majority of these problems after a manifold backfire from the leaky injector. I'm willing to bet it's a huge vacuum leak- what could have "blown out" from it? There was quite a bit of smoke... I'm going to check vacuum, and I'll bet it's really low.
Isn't there a backfire relief valve of some sort? Maybe it didn't reset?
 

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2010 DTS
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87,559 Posts
I think on the '93 & '94 the relief valve is the rubber grommets in the manifold cover. When the manifold is over pressurized the cover lifts some to vent. pull the cover and check the gasket.
 

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1993 ETC, in Windsor, Ont.
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301 Posts
Discussion Starter #10
This has me stumped. I can't find any vacuum leaks. I can hear very quiet clicks from the ISC when I shut the car off, no codes, everything seems to be fine, except it WON'T RUN! lol. It jumps alllll over the place. Sounds like I'm having a seizure on the gas pedal.
 

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2010 DTS
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I can't imagine the ISC motor causing that. A clicking ISC once shut down is an indication of a bad ISC and may cause hunting at idle but once you put your foot on the gas, the throttle linkage pulls away from the ISC plunger. You don't feel the pedal moving under your foot do you?
 

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90 Eldo -SOLD-, 98 ETC -SOLD-, 86 XR4Ti Track Car, 07 Ranger
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963 Posts
I'm not 100% on the intake design of 93 but do you have intake manifold gaskets like the 96+ N*, if so I'd check to see that they're not damaged cause the aren't the strongest pieces in the world and are only held in place by little clips and pressure...

Another thing, due to the backfire I would take off all your front/rear valve covers and make sure all your valves are ok, you never know if you managed to damage one though it would be making an awful racket, you could combine this all and do a compression test, that would also tell you your rings check out...

Did you pull each injector to make sure there weren't any visible signs of damage? You could also use a voltmeter to read the resistance across each injector just to make sure they're all running right (I had a similar problem with idle hunt on a project race car of mine that I tried everything on and it turned out to be an injector out of spec which made it act like a high impedance instead of a low impedance injector which means it was firing but out of sync causing terrible fuel smell/running conditions)
 

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2001 STS
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1,575 Posts
Sidebar: Thanks Ranger for the tips on a leaky FPR. I changed mine (very easy) and the hard starting problem when hot went away immediately. I was astonished how expensive the part was though - $57.
You posted on the 10th bout similiar issue and was able to correct it when changing the fuel pump.
Now post on the 11th saying you changed over the FPR and that fixed.....what ? Thought it was fixed with the fuel pump ?? ......

Anyways..........
Correct me if Im wrong but I didnt think that FPR problems were a prelavant issue in the 93s.
Not saying it couldnt happen. But didnt believe it was an occuring issue in the 93s. Think it wasnt till later years ?
 

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2010 DTS
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I'm not 100% on the intake design of 93 but do you have intake manifold gaskets like the 96+ N*
No, the '93/'94 has a removable cover. The fuel rail and injectors are inside. When the cover is bolted down, there are rubber grommets that the bolts go through and the cover is not torqued down real tight so in the event of a backfire the cover actually lifts and thus vents.
 

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1993 ETC, in Windsor, Ont.
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Discussion Starter #15
So here's the funny thing.... I took off the intake manifold- no FPR problems, injectors are tight/sealed.... I disconnected the battery while I did this of course.
When I reassembled everything, reconnected the battery- it ran FINE. Nice tight idle. (computer was reset) UNTIL I did the TPS relearn...(basically pressing the gas with the ignition on/engine off) then it all went to hell again!
I'm leaning towards a sensor issue.
Ranger- no, the pedal doesn't pulse under my feet.
I'm going to check the TPS data right now.... then tmrw morning I will perform an injector balance test, and if all else fails, bring it to the dealership.
 

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Correct me if Im wrong but I didnt think that FPR problems were a prelavant issue in the 93s.
I don't think the FPR is "prevalent" in any year, but is possible in any year as well. I would think that on a '93/'94 a leaky FPR would pool fuel in the manifold because that is where it is located, filling the manifold with gas fumes and thus be more likely to backfire if it fails. On later years it would leak into the vacuum line and get sucked in AFTER the engine is started, causing it to run rough and rich more than backfiring.
 

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2001 STS
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1,575 Posts
I can't imagine the ISC motor causing that. A clicking ISC once shut down is an indication of a bad ISC and may cause hunting at idle but once you put your foot on the gas, the throttle linkage pulls away from the ISC plunger. You don't feel the pedal moving under your foot do you?
I know what your sayin.
But had a headache myself with that ISC thing.

This has me stumped. I can't find any vacuum leaks. I can hear very quiet clicks from the ISC when I shut the car off, no codes, everything seems to be fine, except it WON'T RUN! lol. It jumps alllll over the place. Sounds like I'm having a seizure on the gas pedal.
93 is old.
I went all over lookin for vacumm leakes. Actually found one. Only because I knew where to look. Was an area that I had been workin round previously.
All the hoses, rubber, everything is britle. Even the connectors !!!
Its to be expected on that age of a vehicle.
Doesnt take much of a jaring to snap and or crack something.

Im not saying the ISC Motor itself per say...
But maybe the electrical connectors that are running from it. The ones that are connected to the rest of the ignition system.

Dont just be thinking vacuum.
Undo the connectors. The male female connector things.

The nightmare I had with after changing my ISC turned out to be "NOT" the ISC Motor....but the connector. And that wreaked major havok on RPM etc....

Dont know whom did the work you said was done when you started this thread.
But do know things had to be moved and disconnected to do it.
And bein a 93, things are brittle and is a chance something aint connected right and or a broken electrical signal.

like said
Its older and things are brittle. The more things are messed with the more chance of disturbing the order of things.

Trust me :eek:

You've already looked at the vaccums. :thumbsup:

Nows time to look at the connectors :highfive:
 

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2001 STS
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.............. TPS relearn...(basically pressing the gas with the ignition on/engine off) then it all went to hell again!
I'm leaning towards a sensor issue.................
Was my understanding your not supposed to touch the throttle whatsoever ??????
 

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2001 STS
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I don't think the FPR is "prevalent" in any year, but is possible in any year as well. I would think that on a '93/'94 a leaky FPR would pool fuel in the manifold because that is where it is located, filling the manifold with gas fumes and thus be more likely to backfire if it fails. On later years it would leak into the vacuum line and get sucked in AFTER the engine is started, causing it to run rough and rich more than backfiring.
Believe it or not I recieced backfire because of the bad connector from the afor mentioned.
Scared the beJesus otta me LOL.
But was still able to cruise the neighborhood at a high rev runnin round 80 KPH.
But damned the engine got hot :eek:
 

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1993 ETC, in Windsor, Ont.
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Discussion Starter #20
Well, made some progress. The signal from the MAP sensor (PCM Data 02) is all over the place, and kept going to open circuit when the engine would stall- turns out the 5 volt reference signal to the sensors from the PCM wasn't quite reaching the MAP sensor all the time. There are a LOT of degraded wires on the car, as I've noticed as I've been tracing this problem. Looks like I'll be selling it soon for something else anyways.
 
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