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slowsc
12-31-2007, 01:39 PM
I have a problem that I can't figure out and would love some advice. I recently purchased a 1991 SC with and automatic trans. The previous owner told me that he was on the highway and this problem started like someone flipped a switch. The car starts no problem and runs up to around 2000 rpms no problem. When I stomp on the gas the car immediatly falls on its face. and breaks up like the timing is off or somthing. I was working on it the other night and noticed that the exhaust was glowing really bright up to the central muffler. ( I think thats what it is at least) The 2 cats and headers were glowing also) I thought that maybe the cats were blocked up so I disconected the exhaust at the headers but that didnt change anything. I have already changed the maf, throttle position sensor and coil with no improvment. Could the Dis control module go bad and cause any of this? I was gonna change the camshaft sensor next but I am getting sick of spending money with no Idea whether it will help with my problem. As far as I know it is not a fuel issue. The fuel pressure stays at alittle over 40psi and never drops. I think it is supposed to raise at high rpms but the car wont rev up that high for that to be the problem. The person I bought the car from said it could be the computer. any advice will be greatly appreciated! One more thing that is confusing me is that the boost still climbs when the rpms drop. Im not familiar with this kind of blower. I have a cefrifugical blower on my mustang and the boost is directly assosiated with the rpms of the motor. curious to know what the difference is.

Young-SC-Owner
12-31-2007, 04:55 PM
it sounds like a vac leak, try starting it and spraing starting fluid around the IC joints and such, the intake and intake plenum, or propane is another thing to use, or you can buy a tool deal from www.spinningwheels-sc.com that pressurizes your intake tract to check for leaks,

hope i helped a little bit

-Tony-

PS have a good new year:rolleyes:

PS where do you live

slowsc
12-31-2007, 05:04 PM
I used a propane cylinder to check all of the vacum lines and didnt notice any surge in rpm's It is very possible that I missed a line or2. Does anyone have a vacum line chart? im From Long Island NY in case anyone knows of a good SC mechanic in my area.

Duffy Floyd
12-31-2007, 07:43 PM
Check and see if the crankshaft pulley is wobbling with the engine running and report back. Sounds to me like your timing is off due to a broken harmonic damper.

the-big-e
12-31-2007, 08:56 PM
I was going to suggest the same thing.....

One way to check for vacuum leaks......

Get a piece of vacuum hose and put one end in your ear and probe around with the other end.....

If there is a vacuum leak, you will be able to hear it.....

Check all around the intake and IC tubes.....

Get yourself some teflon IC gaskets, that should help rule out that area for leaks.....

frdlvr30
01-01-2008, 12:52 AM
I would suggest doing some EEC tests before throwing anymore parts at it. Do both key on engine off (KOEO) and key on engine running (KOER) with a EEC-4 compatable scanner and see if you get anything pointing towards fuel control (Maf, maf connector, hegos) or ignition control (crank position sensor, dis module, camshaft position sensor). This really should always be the first thing done during driveability diagnosis.

Duffy Floyd
01-01-2008, 01:49 AM
Without a CEL it is doubtful reading codes will buy you anything...but do as you want.

frdlvr30
01-01-2008, 02:27 AM
True, However no Cel doesnt mean there are no codes stored in memory or that one can't be produced during the snap test of the KOER. If not you could always check datalogging short and long term fuel trim to verify fuel control is correct and move on from there...that would rule out the vacuum leak theory and point toward DIS, CKP, CPS problem.....

Duffy Floyd
01-01-2008, 02:31 AM
And how would you propose he do datalogging on a 91 SC and what is he going to use to get fuel trim numbers?

frdlvr30
01-01-2008, 02:47 AM
nevermind........

frdlvr30
01-01-2008, 02:51 AM
Duffy has all the answers....after all he has owned a mn-12 for 18 years....nevermind us guys who were actually fixing them for all those years......

jludorf
01-01-2008, 05:17 AM
Now this might sound silly but I had a car that had the glowing cats and it turned out I had a bad plug so the fuel was getting into the exhaust and burning. I was also shooting flames out the exhaust and it would stutter with moderate throttle. Why not pull the plugs to see what condition they are in maybe that will lead to other suggestions. Does the car backfire or anything else? with the front section of the exhaust off is there any fluid comming out of the pipes?

John

KwikGSeX
01-01-2008, 10:27 AM
And how would you propose he do datalogging on a 91 SC and what is he going to use to get fuel trim numbers?

Spiro (aka the original slowsc) was able to get datalogging out of the 89-93 computers..


slowsc what part of Long Island are you from? Im in West Babylon every weekend at my buddy's shop.. We are SC junkies.. I can help you find the problem

fturner
01-01-2008, 10:29 AM
And how would you propose he do datalogging on a 91 SC and what is he going to use to get fuel trim numbers?

Duffy, I'm currently doing that with my '90 and the EEC Tuner board ;). Talk to Dave D and ask him about some of the information I've been giving him as I've been tuning my car.

Paul93SC
01-01-2008, 11:12 AM
My guess is bad fuel pressure regulator, or the vacuum hose connecting it has come off.

Duffy Floyd
01-01-2008, 11:39 AM
Frit,

Interesting......I'll talk to David since I do have a 92 and an ECC Tuner Board and would be interested in being able to datalog. But the point here is it is unlikely that the original poster is going to be able to do datalogging on his car which is the point I was trying to make. Now if someone has a better idea on how a novice can do it I am all ears (or in this case eyes).

Also............I had the exactly same symptoms he described on my 89 when the damper broke hence the reason I suggested he take the steps I did. I also had glowing exhaust manifolds when it happened. Also a broken damper is a relatively common problem for many and can easily be checked for by a novice with these cars. (I noted it was only the second post by the original poster.) But if he can hook-up with Dennis that would be best since I am sure he could help him find the problem.

frdlvr30,

No I don't have all the answers but I have fixed, and helped many who had problems, fix their cars. If you are going to suggest someone take certain troubleshooting steps, it would be nice if you told them how to accomplish what you suggested.

old_coot
01-01-2008, 12:15 PM
Sounds exactly like the problem we were having with Anthony Arnolds car---timing was just so slow all the combustion was taking place in the exhaust---turned out to be the IRCM dropping the voltage to the sensors and the knock sensor pulling the tiiming out---grab a timing light and see if the timing is anywhere near where it should be...................Dan

slowsc
01-01-2008, 01:42 PM
Spiro (aka the original slowsc) was able to get datalogging out of the 89-93 computers..


slowsc what part of Long Island are you from? Im in West Babylon every weekend at my buddy's shop.. We are SC junkies.. I can help you find the problem \
I live in Ridge but I have a trailer that I could bring the car to you with if you think you could figure it out for me. My name is Eddie my cell Phone is 631-433-7295
I did put a scanner on it and it gave me a couple of codes I'll look them up again so I can give you the exact code # but the only code that suggested a specific part was the code for the maf and I already tried replacing it.

KwikGSeX
01-01-2008, 01:53 PM
\
I live in Ridge but I have a trailer that I could bring the car to you with if you think you could figure it out for me. My name is Eddie my cell Phone is 631-433-7295
I did put a scanner on it and it gave me a couple of codes I'll look them up again so I can give you the exact code # but the only code that suggested a specific part was the code for the maf and I already tried replacing it.


Ok you are not THAT far.. My buddy's shop is right off RT. 27 at the 109 exit.. Let me know when you want to come by and I will be around to check it out.. We got a code scanner too so dont worry.. We'll get that SC up and running again!!

slowsc
01-01-2008, 06:52 PM
Ok you are not THAT far.. My buddy's shop is right off RT. 27 at the 109 exit.. Let me know when you want to come by and I will be around to check it out.. We got a code scanner too so dont worry.. We'll get that SC up and running again!!

Let me know what night and what time and I'll be there. you can call me if you want to confirm it but if you post a day and time I will be there without talking to you on the phone. just give me directions. I broke the studs that connect the exhaust manifolds to the mid pipe so if you you guys want to fix that also be my guest :) When I bring it to you take a look and let me know what you will charge me to get it right. If you want me to leave it I can do that also. Thanks! I'll talk to you soon!

--Eddie