93 Deville

[beefy]

Ive been posting on another forum for years but recently noone reads it, so Im hoping this can be my new home. Heres my issue:

The engine was surging alittle bit and even stalled once and a while when idling. After got an ISC code and the poor idling I changed the ISC actuator, heres whats up as of now:

-When I start the car it revs way up to about 2500 RPMs then drops down slowly to its normal "Idle" of around 900.

-At idle theres a noticable knock and a shimmy everytime the engine knocks I can feel the vibration in the steering wheel(as well as the rest of the car)

-When I rev the engine from a stop (as if starting at a light) the car sounds loud, I think its detonating, not sure what it sounds like tho. Also most of the time at around 2000 RPMs theres a weird buzzing in the gas pedal.

-At cruising speed, there is still a shimmy any detonating is less noticable, if any at all, if at above mentioned RPMs buzzing is less frequent.

- If car is idling and at a stop, the engine will begin to surge after being on for about 30 seconds. If while parked I rev it to about 2500 then let my foot off the gas, the RPM's will drop slowly and there will be a backfire out the intake, most of the time it will be slight.

-If while cruising I give it alot of gas, say to pass someone, I will either get a slight gas odor or a sulfur smell, sometimes both.

What Ive done to the car since I bought it- Oxygen sensor, fuel filter, air cleaner, and front brakes, and the ISC, engine flush and oil change to come next. Any thoughts? IF I were tune it up think Someone can tell me easy ways to get to the firewall side of the engine's spark plugs? THANKS

Ok sorry for the multiple posts but that was posted in the other forum maybe 2 weeks ago, things have gotten slightly worse since then. Ive had the timing checked, the guy said it was dead on. My car has 118000ish miles, other than the knock it runs beautifully, But the knock is slowly getting worse. The dealers in my area charge 450$ diagnostic fee and 110$/hr labor. So I dont want to dump loads of money into this car without having it actually fixed. But I do want to get it fixed before it starts to burn oil. I bought the car 3 months/4000 miles ago, and I didnt notice a knock then at all. Oh and when it backfires the car will actually lurch forward, I thought that was weird. Anyway I wait for the expert opinions, thanks in advance.

[Ranger]

The knock could be" main bearing thump". Annoying but harmless. Back off the tension just enough to let the belt slip. If the noise goes away that is the problem. If it is, Rotella or Delvac 15W40 may help quiet it down. A replacement bearing can also be installed if you want to spend the money.

Was the replacement ISC motor new? Was is A/C Delco? Was it adjusted after instalation? Have you checked and cleaned the EGR tubes? Have you checked the FPR?

There IS no easy way to get to the rear plugs.

[beefy]

Main bearing thump huh, never heard of that. Tomorrow Ill try that belt trick and see if it still knocks. The ISC, wasnt a Delco, I bought it from Autozone so whatever their house brand is. It was a new part though. As for adjusting it, I was told to start the car let it run for 30 seconds then shut it down and start it again, that should have adjusted it. As for the egr, i pushed the plunger in by hand and the engine started to choke and when i released it the engine revved back up, i figured this to be normal. With the engine running I pulled the pcv hose off and the revs shot wayyyy up but the engine didnt die. this wasnt unusual to me but a guy a the autozone said it shouldve died. Its weird Im not sure if this is related but the engine seems to want to rev easier then drop in revs. When in park if i tap the gas the engine will race way high then drop extremely slowly. Oh and whats Rotella? and FPR is Fuel Pump Reg? I dont know how to check that without a pressure gauge.

[adallak]

Despite you did not follow the correct ISC motor adjustment procedure it sounds normal. I would start with cleaning throttle body and blades along with two EGR tubes inside the throttle body (as Ranger mentioned). The knocking at LIGHT throttle when engine is HOT is most likely EGR related. The fact the engine nearly stalled when you pushed the EGR valve manually indicates the EGR passages are not restricted. But the EGR valve, EGR solenoid and all the vacuum lines from the TB should be checked for integrity. Main bearing thump is harmless.

You can replace rear plugs by laying across the engine. They are actually easier to work with than the front ones because there is more room up there.

Unstable idle might be caused with leaking injectors. How's your fuel economy and what is your driving pattern (town, high way).

[thu]

Beefy,

At this point, a Factory Service Manual would be priceless to you esp if you're doing your own work. Helm is having a 50% off sale on their 1990 to 2000 FSMs. These are the original GM/Cadillac Service Manuals.

I have a 1993 Deville just like you and the FSM has been very valuable and educational.

You want this part number: H2914 (1992-93 Deville/Fleetwood/Sixty Special Service Manual). Here is the table of contents: http://www.helminc.com/helm/assets/TOC/H2914.htm

Go to www.helminc.com.

The FSM has COMPLETE troubleshooting trees, diagnoses, etc.

[beefy]

My fuel economy is HORRIBLE, I avg about 8mpg and i drive very very town. My job has me driving 5 hours a day through brooklyn streets. If I take a 35-45- minute trip on a highway where i can cruise most of the way then my avg jumps to a whopping 9.2 tops. I never thought about the fuel economy as a symptom though because I had an 86 deville a while back and it had a smaller motor and i averaged 10-11 MPG. I can check the vacuum hoses easy enough, the egr valve I only know to check with a hand pump to actuate it, is there some garage trick I can try? I know I have transmission problems, is it possible that "backfire" I hear after i keep the engine revved for a few seconds is a transmission problem, becaus the car DOES lurch. That manual sounds like an awesome Idea thanks thu.

[adallak]

My fuel economy is HORRIBLE, I avg about 8mpg and i drive very very town. My job has me driving 5 hours a day through brooklyn streets. If I take a 35-45- minute trip on a highway where i can cruise most of the way then my avg jumps to a whopping 9.2 tops. I never thought about the fuel economy as a symptom though because I had an 86 deville a while back and it had a smaller motor and i averaged 10-11 MPG. I can check the vacuum hoses easy enough, the egr valve I only know to check with a hand pump to actuate it, is there some garage trick I can try? I know I have transmission problems, is it possible that "backfire" I hear after i keep the engine revved for a few seconds is a transmission problem, becaus the car DOES lurch. That manual sounds like an awesome Idea thanks thu.

Looks like you have a bunch of problems. To measure fuel economy correctly on high way you should reset it. I suspect your fuel injectors are leaking. Pretty common on old 4.9 engines. Fortunately you can replace all of them with ones from Crown Vic for about $250 at fivemotors.com or something like that. Transmission sounds bad, it might be sprug. BBF (BodyByFisher had similar issue). Another easy check. The FPR may leak as well. Idle the engine and pull the vacuum line attached to its nipple. Any presence of fuel indicates a leaky fuel pressure regulator.

[Ranger]

Oh and whats Rotella?

Rotella & Delvac are motor oil. Rotella is Shell. Not sure who makes Delvac.

FPR is Fuel Pump Reg?

Fuel Pressure Regulator. It is a small canister mounted on the fuel rail with a vacuum hose to it. With the engine at idle, pull the vacuum hose off. If there is any sign of fuel at the nipple, depressurize the fuel rail and R & R the FPR (after you shut the engine down of coarse).

I was told to start the car let it run for 30 seconds then shut it down and start it again, that should have adjusted it.

Wrong, with the engine at idle, push on the ISC plunger til it retracts and bottoms out. When it does, unplug it. Now adjust the plunger to a .030 gap with the throttle linkage and then plug it back in.

[KHE]

My fuel economy is HORRIBLE, I avg about 8mpg and i drive very very town. My job has me driving 5 hours a day through brooklyn streets. If I take a 35-45- minute trip on a highway where i can cruise most of the way then my avg jumps to a whopping 9.2 tops. I never thought about the fuel economy as a symptom though because I had an 86 deville a while back and it had a smaller motor and i averaged 10-11 MPG. I can check the vacuum hoses easy enough, the egr valve I only know to check with a hand pump to actuate it, is there some garage trick I can try? I know I have transmission problems, is it possible that "backfire" I hear after i keep the engine revved for a few seconds is a transmission problem, becaus the car DOES lurch. That manual sounds like an awesome Idea thanks thu.

10 MPG is abnormally low for that car - I would expect at least 18 in the city and 23-24 on the highway.

[PAUL T]

I would vote for a faulty Fuel Pressure Regulator. It is easy to check. Pull the hose and see if gas is present. You might check the Catalytic converter also, It could be plugged.

[epricedright]

I have the #1 main bearing thump, but it does NOT make the car vibrate (at all). The noise will get worse when the engie is hot while under load, but with fresh Rotella 15W40, the noise is almost non-existant. Not ruling out the #1 main baring thump though, as all cars are different. Maybe your noise is EGR related and not anything major.

Sounds like you have multiple problems. I'd take one thing at a time. To sum up what others have already suggested, I would:

1. Check for codes.

2. Disconnect your negative batt cable before cleaning TB to reset idle for a clean TB

3. Clean your throttle body and the 2 EGR tubes thoroughly. Use a hanger or gun cleanig tip to "rod out" the tubes and make sure they're clear back to the EGR valve. Use intake cleaner, and not choke cleaner.

4. Reconnect batt cable.

5. Check your ISC motor like Ranger advised, being sure it's adjusted correctly. Hopefully, your non-oem ISC is working correctly.

6. Check your EGR valve, EGR solenoid, vac lines, FPR, catalytic converter.

7. Check your #1 main bearing thump by having someone power break, inducing the noise, then loosen your belt tensioner with a 1/2" breaker bar or ratchet. If the noise goes away with the belt loosened, then it's your #1 main.

8. If you have the #1 main thump, change your oil using Rotella or Delvac 15W40. Wal-Mart has them both.

[beefy]

I have the #1 main bearing thump, but it does NOT make the car vibrate (at all). The noise will get worse when the engie is hot while under load, but with fresh Rotella 15W40, the noise is almost non-existant. Not ruling out the #1 main baring thump though, as all cars are different. Maybe your noise is EGR related and not anything major.

Sounds like you have multiple problems. I'd take one thing at a time. To sum up what others have already suggested, I would:

1. Check for codes.

2. Disconnect your negative batt cable before cleaning TB to reset idle for a clean TB

3. Clean your throttle body and the 2 EGR tubes thoroughly. Use a hanger or gun cleanig tip to "rod out" the tubes and make sure they're clear back to the EGR valve. Use intake cleaner, and not choke cleaner.

4. Reconnect batt cable.

5. Check your ISC motor like Ranger advised, being sure it's adjusted correctly. Hopefully, your non-oem ISC is working correctly.

6. Check your EGR valve, EGR solenoid, vac lines, FPR, catalytic converter.

7. Check your #1 main bearing thump by having someone power break, inducing the noise, then loosen your belt tensioner with a 1/2" breaker bar or ratchet. If the noise goes away with the belt loosened, then it's your #1 main.

8. If you have the #1 main thump, change your oil using Rotella or Delvac 15W40. Wal-Mart has them both.

Thanks for the list that will make my life alot easier I already know theres no codes, the only codes I got on the car when I bought it was a tps code and the ISC code. After I replaced the battery about 1000 miles ago the tps code never came back but the ISC did, and I replaced it. And now no codes at all. As for the rest of that stuff to look for Im waiting for dry weather Ill keep you guys posted. And its almost time to change my oil, the car has so many miles on it, whats the thickest oil I should dare use on it? Also is that oil stabilizer stuff harmful to my engine?

[epricedright]

The thickest I'd go with is 15W40. Try that Rotella or Delvac 15W40 if you suspect you may have that "thump". Even if you don't, it won't hurt. I don't think you need any oil stabilizer. I would try to determine if you have the #1 main bearing thump by loosening the belt tensioner while someone (you trust) power breaks it, before changing your oil, just to see if you have it or not.

[beefy]

The thickest I'd go with is 15W40. Try that Rotella or Delvac 15W40 if you suspect you may have that "thump". Even if you don't, it won't hurt. I don't think you need any oil stabilizer. I would try to determine if you have the #1 main bearing thump by loosening the belt tensioner while someone (you trust) power breaks it, before changing your oil, just to see if you have it or not.

Ok thanks, Ill see if costco or autozone has that oil you suggested, again waiting on no more soggy mess of a day, I think late tomorrow. And by power breaking you mean what exactly? I was just gonna keep it in part with the parking breake on and wedge the gas pedal down a bit.

[adallak]

The thickest I'd go with is 15W40. Try that Rotella or Delvac 15W40 if you suspect you may have that "thump". Even if you don't, it won't hurt. I don't think you need any oil stabilizer. I would try to determine if you have the #1 main bearing thump by loosening the belt tensioner while someone (you trust) power breaks it, before changing your oil, just to see if you have it or not.

Ok thanks, Ill see if costco or autozone has that oil you suggested, again waiting on no more soggy mess of a day, I think late tomorrow. And by power breaking you mean what exactly? I was just gonna keep it in part with the parking breake on and wedge the gas pedal down a bit.

Wal-Mart stocks 15w-40 as well. Powerbraking is pressing gas pedal while in D or R with your left foot FIRMLY on the brake pedal.

[epricedright]

The thickest I'd go with is 15W40. Try that Rotella or Delvac 15W40 if you suspect you may have that "thump". Even if you don't, it won't hurt. I don't think you need any oil stabilizer. I would try to determine if you have the #1 main bearing thump by loosening the belt tensioner while someone (you trust) power breaks it, before changing your oil, just to see if you have it or not.

Ok thanks, Ill see if costco or autozone has that oil you suggested, again waiting on no more soggy mess of a day, I think late tomorrow. And by power breaking you mean what exactly? I was just gonna keep it in part with the parking breake on and wedge the gas pedal down a bit.

Costco has one of those, can't remember which, but you have to buy a large quantity. Wal-mart has both.

By power braking, I meant for you to have someone else in the car, while the car is in drive, have one foot solidly on the brake and the other foot on the gas. Maybe chock the wheels to be safe. With the brakes firmly on, rev it to put strain on the motor, to induce the noise. While someone is doing that, you need to loosen the belt tensioner slightly with a 1/2" breaker bar and see if the thump goes away. The belt will squeal when you do this, but you should still be able to hear the thump go away, if it's the #1 main bearing.

[beefy]

Theres no walmart close to me, so Ill haveto hunt it down, What does it mean if my transmission is sprug? Are these the crown vic Injectors youre talking about?

Bosch Injectors - 0280150556 D5B-19lb*

8/Set: $229.

from www.fiveomotorsports.com ?

[adallak]

Theres no walmart close to me, so Ill haveto hunt it down, What does it mean if my transmission is sprug? Are these the crown vic Injectors youre talking about?

Bosch Injectors - 0280150556 D5B-19lb*

8/Set: $229.

from www.fiveomotorsports.com ?

Yes, they are 19 lb, but looks like they sell them for $299 for 8 set. Give them a call. The sprug is a part of transmission. That's just a suggestion. I believe BBF had similar symptoms when his tranny failed.

You can check injectors for leaks by lifting the fuel rail and turning ignition ON (engine OFF). There should be no fuel coming from injectors.

[beefy]

Am i looking for leaks into the combustion chambers or onthe the manifold? If im looking for leaks onto the manifold how is it getting burnt and making my engine surge

[adallak]

Am i looking for leaks into the combustion chambers or onthe the manifold? If im looking for leaks onto the manifold how is it getting burnt and making my engine surge

Injectors leak into combustion chambers. Lifting the rail with injectors up will make leakage visible when the fuel system is pressurized, in other words when ignition is tuned ON (engine OFF).

[beefy]

Am i looking for leaks into the combustion chambers or onthe the manifold? If im looking for leaks onto the manifold how is it getting burnt and making my engine surge

Injectors leak into combustion chambers. Lifting the rail with injectors up will make leakage visible when the fuel system is pressurized, in other words when ignition is tuned ON (engine OFF).

Ok I cant get anyone to sit behind the wheel for me, so Im just gonna put the Rotella in it and see if the noise goes away. If I use that canned engine flush stuff before I change the oil, will that harm my car? On that website for five0motorsports.com It showed Injectors for my car 8set 300, but someone posted that i could use the 19lb crown vic injectors... theyre listed for 229 I think, theyre in my above post. Can someone clarify that for me? I pulled the fuel rail real quick during my lunch brake and saw at least 2 leaking injectors, at any parts store thats like 200 right there. Speaking of breaks, mine suck... they wear out in a month, I put about 1200 miles on the car a month. Autozone sells "heavy duty" pads which are bigger than the normal pads, I assume I haveto change the rodors and calipers for that? Can anyone reccomend anyway to increase pad life cheaply? Can I just throw some semi-metallic pads on it? I was toying with the Idea of converting the rear drums to Disc... Ok thats alot for tonite thanks again.

[epricedright]

Am i looking for leaks into the combustion chambers or onthe the manifold? If im looking for leaks onto the manifold how is it getting burnt and making my engine surge

Injectors leak into combustion chambers. Lifting the rail with injectors up will make leakage visible when the fuel system is pressurized, in other words when ignition is tuned ON (engine OFF).

Ok I cant get anyone to sit behind the wheel for me, so Im just gonna put the Rotella in it and see if the noise goes away. If I use that canned engine flush stuff before I change the oil, will that harm my car? On that website for five0motorsports.com It showed Injectors for my car 8set 300, but someone posted that i could use the 19lb crown vic injectors... theyre listed for 229 I think, theyre in my above post. Can someone clarify that for me? I pulled the fuel rail real quick during my lunch brake and saw at least 2 leaking injectors, at any parts store thats like 200 right there. Speaking of breaks, mine suck... they wear out in a month, I put about 1200 miles on the car a month. Autozone sells "heavy duty" pads which are bigger than the normal pads, I assume I haveto change the rodors and calipers for that? Can anyone reccomend anyway to increase pad life cheaply? Can I just throw some semi-metallic pads on it? I was toying with the Idea of converting the rear drums to Disc... Ok thats alot for tonite thanks again.

Do yourself a favor and leave Autozone alone, especially their "lifetime" brake pads, starters, alternators, etc., etc.

Who has been doing your brakes? Have you had your rotors turned or replaced? Bad rotors (gouged) can cause premature pad wear. But it sounds like you have a sticking caliper slide(s) or a sticky caliper piston causing premature pad wear. Something is sticking and not allowing your pads to "float" away from your rotors - there is definately something wrong.

I use Raybestos Quiet Stop ceramic pads and Raybestos Quiet Stop rotors and love them. Rockauto carries them. Before replacing your pads, have your brake system checked out thoroughly. Make sure they're using Silicone grease in your rubber slider bushings.

[winterset]

Poor gas mileage, breaks wearing exceptionally, fast. Does sound like a piston is stuck indeed. I will inspect all the brake sliders, bushings etc. that should add a few MPG.

[beefy]

I just figured since Im fighting the engine every time I try and stop because the darn revs dont wanna drop(leaky injectors) My pads were wearing faster... Ill pull the wheels off when I change the oil and inspect the brakes, One thigns for sure Im doing most of the work myself now, I had the brakes changed at a gas station I used to trust... I learned theyve been shafting ppl recently, under new management apparantly. As for staying away from autozone Im afraid thats hard to do, the only auto parts stores I really have nearby are autozone and strauss... theres a pep boys but its about 45 minutes away.

[Patrick7997]

It doesn't really matter which parts store is near you... epricedright just pointed out that the Raybestos products he mentioned are available online at rockauto.... It only matters in a dire emergency....

I tend to agree that there is a brake issue there, and I would urge you to address that. Get the caliper slider pins cleaned up and fully lubed with the correct silicone grease, put new rotors & new pads to start fresh, and go from there....

That ISC motor also has to be addressed. I was sold a bad one once, new in the box, so if it doesn't seem right, take it back & get another one, and follow Ranger's advice on how to set it up...

After that stuff is fixed, then you can move on to the injectors...

Good luck....