Advanced Tech Advanced tech discussion. Major rebuilds, engine theory, etc.
HIGH-END DISCUSSION ONLY - NOT FOR GENERAL TECH INFO

The infamous obd1/high stall converter problem

Thread Tools
 
Search this Thread
 
Old Dec 19, 2001 | 06:07 PM
  #1  
big dave's Avatar
Thread Starter
Registered User
 
Joined: Apr 2000
Posts: 564
From: Silver Spring ,Md.
Post The infamous obd1/high stall converter problem

If anyone on this board would have a solution to this problem, you guys will. Apparently there is a problem with the obd1 cars (94-94 fbodys) having a converter higher than 2800 stall speed. I was somehow hoping that this wouldn't affect me so while my tranny was out for repair, I decided to have my stall speed raised to 3200. I guess I wasn't immune. At the track, if the car hooked, the tranny wouldn't shift from 1-2. Then it would go into some kind of a limp home mode where the overdrive wouldn't work until the car was restarted. After sending the computer out to Ed Wright for reprogramming and having that not fix the problem, decided to have the converter destalled back to the original 2800 stall speed. Have you guys dealt with this problem and what do you think it is and what do you think might be a possible solution?

------------------
94 Z28 auto.White with white wheels.A few mods. 12.13@113 N/A with a 1.71 60'on nittos
Old Dec 19, 2001 | 06:25 PM
  #2  
96 Comp T/A's Avatar
Registered User
 
Joined: Dec 2000
Posts: 39
From: Lutz, FL
Post

Convert to an OBD2 PCM. This is a proven remedy. Look it up in the LT1edit archives from about 2 months ago. A lot of people tried a bunch of different things and this is what fixed it.

------------------
96 Comp T/A #84 of 172
LS1 brakes, LT1_edit for OBDII.
TNT plate kit, a4 to M6 in progress!!!, Hooker LT's !anything not serving a go-fast purpose.
Old Dec 20, 2001 | 01:45 AM
  #3  
89ProchargedROC's Avatar
Registered User
 
Joined: Aug 2000
Posts: 556
From: Chicago, IL
Post

i've never had a problem with people with cars around me

we dont even use the computer to supply the line pressure anymore, we use a transgo vacuum modulator kit and dont have problems

its better off for the tranny in the end too and less troublesome than converting to OBDII
Old Dec 20, 2001 | 08:33 AM
  #4  
Kraest's Avatar
Retired
 
Joined: Oct 1999
Posts: 3,166
From: Inside Uranus
Post

<font face="Verdana, Arial" size="2">Originally posted by 89ProchargedROC:
i've never had a problem with people with cars around me

we dont even use the computer to supply the line pressure anymore, we use a transgo vacuum modulator kit and dont have problems

its better off for the tranny in the end too and less troublesome than converting to OBDII
</font>

Do you have to shift it yourself? I was running a similar setup, but had to shift it myself.

Some of the bracket racers (the only reason to even THINK about going with an automatic, IMO) didn't want to shift it, so they did the OBDII.

Mike

------------------
1994 Sunset Orange Metallic Camaro Z28 Convertible - The Gorgeous and Sadistic Bitch Who Mistreats You and Lets You Down, Yet You Still Keep Her


1989 Red Ford Mustang LX 5.0 Convertible - The Dependable Girl Who Treats You Right, Yet Your Mind Wanders Elsewhere
Old Dec 20, 2001 | 11:21 AM
  #5  
kevkop94TA's Avatar
Registered User
 
Joined: Aug 2001
Posts: 370
From: Dirty Jersey
Red face

big dave- You told Ed that the stall was a 3200? I'm surprised cause what I heard on this board was that he could fix it by adjusting the trannt tables. I'm a little worried now as I planned on 3500 stall with my heads/cam.
Old Dec 20, 2001 | 11:26 AM
  #6  
big dave's Avatar
Thread Starter
Registered User
 
Joined: Apr 2000
Posts: 564
From: Silver Spring ,Md.
Post

Yes, I did tell him it was a 3200. Apparently he redid the programming to change the gears by reading rpms instead of reading speed. It has something to do with the vss. Another interesting note was when I was going to get the obd2 computer from him, I was told that I would have to not only change the knock sensor but also a couple other things. Apparently with the 95 computers, it is far easier to do the conversion. I always thought the 94s and 95s were the same but apparently not.
Old Dec 20, 2001 | 11:29 AM
  #7  
big dave's Avatar
Thread Starter
Registered User
 
Joined: Apr 2000
Posts: 564
From: Silver Spring ,Md.
Post

KRAEST, now I didn't have to shift it by myself. It wouldn't allow me to do that. When I attempted manual shifts the same problem occurred.
Old Dec 20, 2001 | 05:24 PM
  #8  
89ProchargedROC's Avatar
Registered User
 
Joined: Aug 2000
Posts: 556
From: Chicago, IL
Talking

<font face="Verdana, Arial" size="2">Originally posted by Kraest:

Do you have to shift it yourself? I was running a similar setup, but had to shift it myself.

Some of the bracket racers (the only reason to even THINK about going with an automatic, IMO) didn't want to shift it, so they did the OBDII.

Mike

</font>
No, you dont have to shift it yourself. The stock OBD I computer STILL shifts the transmission at whatever rpm it is programmed at

BUT

line pressure is now controlled by a vacuum modulator reading TRUE ENGINE VACUUM do give the proper line pressures.

Trans go sells the kits to convert to this style for about $110 from trans shops that are local to you and install isn't hard
Old Dec 21, 2001 | 04:42 PM
  #9  
a_z28_vance's Avatar
Registered User
 
Joined: Feb 2000
Posts: 190
From: Collinsville/Maryville IL
Post

<font face="Verdana, Arial" size="2">Originally posted by 89ProchargedROC:
No, you dont have to shift it yourself. The stock OBD I computer STILL shifts the transmission at whatever rpm it is programmed at

BUT

line pressure is now controlled by a vacuum modulator reading TRUE ENGINE VACUUM do give the proper line pressures.

Trans go sells the kits to convert to this style for about $110 from trans shops that are local to you and install isn't hard
</font>
Do you happen to have the part #?? What if you have a hotcam, will that effect the vacuum pressure much?? In my IROC, I had to install a vacuum canister for my brakes b/c of the cam.
Old Dec 22, 2001 | 11:06 PM
  #10  
Pro Stock John's Avatar
Registered User
 
Joined: Mar 1999
Posts: 659
From: Chicago, IL
Post

I have read this before, and it makes no sense to me.

Also, Pureevil (pureevil79@aol.com), a moderators on this ubb, ran at least a 4000 stall in his 95 LT1 TA last year and had no problems.

Is it me or were most of the cars having problems using LT1 Edit?

ODDII is even more complicated IMHO.

John
11.1 na LS1


Old Dec 23, 2001 | 01:19 AM
  #11  
89ProchargedROC's Avatar
Registered User
 
Joined: Aug 2000
Posts: 556
From: Chicago, IL
Post

<font face="Verdana, Arial" size="2">Originally posted by a_z28_vance:
Do you happen to have the part #?? What if you have a hotcam, will that effect the vacuum pressure much?? In my IROC, I had to install a vacuum canister for my brakes b/c of the cam.</font>
doesn't matter what cam you run because in actuality, the lower the vacuum reading at idle the more line pressure there will be in the tranny anyway which is a GOOD thing

no i dont have a part #

call your local transshop
Old Dec 23, 2001 | 05:26 PM
  #12  
Z2FAST8's Avatar
Registered User
 
Joined: Feb 2001
Posts: 13
From: Blackwell, OK
Post

When I hammer it from a slight roll it seems like the tranny is slipping. Then I let off the throttle and get back in it and its fine. Also the ABS light comes on and stays on till I turn off the car

------------------
94 a4,3.23,K&Nfilter, 80 series Flowmaster, no cat, Jet 2 chip, Transgo shift kit, TT3000 w/2.5 str

87 GN ~106k
air bag pass side, pinion snubber, boxed trailing arms with polygraphite bushings, trans has Art Carr line pressure mods and shimmed servo, Precision 210/205 cam with new lifters, springs, and roller timing chain, and roller thrust button, blue top 36lb injectors, modified plenum, Red Armstrong ign wires, XP fuel pump, and 93 chip, K&N 12in intake breather, engine breathers (2), tiedown, alky injection

The only replacement for displacement is BOOST.
Old Dec 24, 2001 | 12:45 AM
  #13  
OneFlyn95z28's Avatar
Registered User
 
Joined: Dec 1969
Posts: 1,431
From: Pacific North West
Question

PSJ if it were just LT1 Edit WHY would Ed Write be having the problem also he Hex edits

OBD II is not as bad as many think and has some good advantages

Later

------------------
11 Seconds to LOVE!
Mod's? A little of this and some of that.
Beware of what you can not see
My Ugly Old Ride
REAL racers Site
Old Dec 24, 2001 | 01:36 AM
  #14  
89ProchargedROC's Avatar
Registered User
 
Joined: Aug 2000
Posts: 556
From: Chicago, IL
Post

personally, i think you are all nutz

We never had a problem with trannies blowing up (high performance ones with big stalls) at my shop unless it made a lot of hp and it DIDN'T have the vacuum modulator

then YES

it would burn up in a few months or less

but with the modulator, we dont ever really have comebacks
Old Dec 24, 2001 | 02:37 AM
  #15  
a_z28_vance's Avatar
Registered User
 
Joined: Feb 2000
Posts: 190
From: Collinsville/Maryville IL
Post

<font face="Verdana, Arial" size="2">Originally posted by Z2FAST8:
When I hammer it from a slight roll it seems like the tranny is slipping. Then I let off the throttle and get back in it and its fine. Also the ABS light comes on and stays on till I turn off the car

</font>
That sounds exactly like my car last April. Eventually I lost OD, then D, followed by 2nd, and finally 1st. Turned out to be my TC and it had came apart and destroyed the tranny. Good thing the shop rebuilt it for free again b/c of their crappy TC.

PSJ, I have heard of a couple people NOT having problems with the 1-2 shift at WOT w/ a stall of 3200 or higher, but that has been few and far inbetween.



All times are GMT -5. The time now is 07:47 PM.