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Discussion Starter #1
Greetings all... I was wondering, I recently bought a 1990 deville. 215k on her, but looks & runs fine. I went to get a sticker and it was hign on the HC part of emissions. The limit is 2.00 & it came in at 9.04, which failed me. All the others were well under spec. I've replaced the ICS, because the other was ratcheting against my foot while driving. When I bought the car, the guy turned the screw all the way in to lower idle speed, due to racing. Then I checked codes & code 22 came up, open TPS circuit. I replaced the TPS and idle is still not working, so the adjusting screw is all the way in for a non racing engine. I still get code 22 from time to time, mostly when it warms up. Could this be why my emissions are high? From a little faster idle? The High HC reading came from deceleration portion of the drive cycle during the test. May new plugs cure the problem? The air cleaner is pairly new & clean. I really hope it's not the cat converter, since I have dumped a lot of cash into this car already.
Any suggestions to lower the HC emissions, would greatly appreciated....
 

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2005 CTS-V, 1994 Infiniti Q45
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I dont think the TPS is causing the problme. Its possible that the TPS isnt adjusted right or the harness is loose..... try wiggling the connecotr......

Other than that, I think HC are from the cat... However, new plugs and wires could cure it and its DEFINITELY a good idea, especially if it hasnt been done recently..... Id change the plugs and wires REGARDLESS, unless its been done in the last 50k or so.....
 

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1968 Cadillac Sedan deVille, 1994 Chevrolet G20
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HC is usually caused by running too rich. The TPS COULD cause it, but considering the mileage, i'm more inclined to think its dirty sticking injectors, or a bad fuel pressure regulator. If it is running rich, fix it soon or else you WILL need a new cat.
 

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Discussion Starter #5
Thanks Guys, for the input. I'm still at a loss on what to do, but 1st, I'll run some fuel injector cleaner in and run the tankfull through. Any suggestions on what is the best product to use?
Then after a tank or two, I'll change the plugs, don't wanna run new plugs while it's burning gunk. Since I have 60 days to correct this, the last resort, I'll get some of that stuff that guarantees pasing emmisions and run a tank of that, then retry test.
I still can't get the ICS to move at all and after trying to re adjust the TPC, still get the error code E22, which is TPS open circuit. I'm not sure what to do with that one.
Anyone know how to adjudt the TPS? I loosened the mounting screws, adjusted the ICS plunger all the way in, so the throttle stop is almost hitting the idle stop screw, then opened the throttle plate fully, then let it snap back so it would let the TPC adjust itself then set it in that position. Am I on the right track here?

In any event, thanks for all the input you guys gave me. I wanna keep my Caddy and not go to a Lincoln :rolleyes:
 

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2005 CTS-V, 1994 Infiniti Q45
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BG44K is the best on the market, order only..... However, dont expect fuel injector cleaner to do anything for you.... They are designed to keep clean systems clean, not to clean dirty sytems..... You may or may not see a marginal difference, but for $5 you cant go wrong for the cheap stuff ($17 for BG44k, but it does work)...

Im not sure on the TPS adjustment ill wait for someone to key in there......
 

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DeathWish said:
Thanks Guys, for the input. I'm still at a loss on what to do, but 1st, I'll run some fuel injector cleaner in and run the tankfull through. Any suggestions on what is the best product to use?
Then after a tank or two, I'll change the plugs, don't wanna run new plugs while it's burning gunk. Since I have 60 days to correct this, the last resort, I'll get some of that stuff that guarantees pasing emmisions and run a tank of that, then retry test.
I still can't get the ICS to move at all and after trying to re adjust the TPC, still get the error code E22, which is TPS open circuit. I'm not sure what to do with that one.
Anyone know how to adjudt the TPS? I loosened the mounting screws, adjusted the ICS plunger all the way in, so the throttle stop is almost hitting the idle stop screw, then opened the throttle plate fully, then let it snap back so it would let the TPC adjust itself then set it in that position. Am I on the right track here?

In any event, thanks for all the input you guys gave me. I wanna keep my Caddy and not go to a Lincoln :rolleyes:
Hope you don't have the same problems I had 4 years ago with my 90 Deville. It wouldn't pass emissions (don't remember what the exact prob was) but Sun Devil Auto (I would NEVER, EVER use them again) charged me $2100 for 8 new fuel injectors, O2 sensor, Catylitic Convertor, etc.
 

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Discussion Starter #8
I rebuilt my ICS so now the plunger is smooth moving back & forth. I positioned the new TPS according to the marks on the old one, and now my idle sets itself to a fast idle when cold, then idles down to normal. I also don't get the code E22, which is TPS open circuit. I'm still having trouble with the FDC cycling erratic, stationary or moving, but it may be a bad ground. I hope the BCM isn't going bad. I sometimes get error code F31(FDC/DDC To BCM Data CKT) Anyone ever had this code show up & if so, what exactly does it mean?
I still haven't done anything about the high HC that failed me, but thats next on the list. Going to get Ac plugs (OEM) and some of that BG44k and run that through. Hopefully that will help, I hope. If it don't pass emissions, I'm screwed.
 

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I've always had a philosophy that you fix whatever you find and see if the original problem is still there. Possibly the things you found were causing the computer to run in open loop mode where it just makes a educated guess at what the engine needs and doesn't use all the sensor inputs. If that and a set of plugs don't solve your problem, I would suspect a bad oxygen sensor. When the engine is running on closed loop, the oxygen sensor has the greatest influence on the mixture.
 

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Have you passed the inspection yet? My 98 Deville is due for inspection now. I will do a fuel injector cleaning, run some BG44k, and change the plugs and wires. I am concerned that I may run into emission problema also. I will also use some of the fuel additive to reduce emission.

Good luck to you, and to me also.
 

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If you are swapping out the plugs and wires, change your oil right before you go and get it tested. I had a Chevy 3.1 that had HC off the chart that failed like 2 times. I tried all those additives but to no avail. I called a mechanic, who was to busy to look at my car, and he said change the plugs and wires. He kept stressing to change the oil and then take the car immediately in to test. For me it worked like a charm. I had a spark plug wire get up next to the manifold. I think my HC readings went from like 420 to 12.
 

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The idle speed control motor acts as a dashpot when you let off the throttle to prevent overrun misfire due to the throttle being closed too far too fast too abruptly. If the ISC is not working it could definitely cause the problem with high HC.

Fix the ISC so it operates correctly, first. Do a search using "ISC" or "idle speed control" or "idle speed control motor" and read up on some of my posts. There are some good descriptions of how to check and set up the idle speed control motor.

Did you clean the throttle body bores and the EGR tubes. The EGR tubes can be plugged and cuase a misfueling problem that could indirectly lead to the HC problem. If the throtttle body is dirty it will also confuse the idle speed control and cause problems. Clean both thoroughly and disconnect the negative battery cable. Plenty of info in search on "EGR tubes" and "Cleaning throttle body"

Several recent posts on high HC and emissions problems...did you look down the list of threads over the past few pages...???

Check the fuel pressure regulator for seepage past the vacuum diaphragm into the vacuum hose into the intake manifold.....once again, plenty of info on the FPR in search.

Forget the additives and gas treatment. Tend to the basics instead of relying on snake oil.



BTW...before you take it to be tested the next time take the car out and give it a thorough run up thru the gears several times to clean the exhaust out, get the engine thoroughly warmed up and the oil HOT and to get the exhaust system good and hot. The cat conv only works when hot so get it hot before taking it to be tested. Don't stop on the way and park and wait.
 
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