93 bonneville sc 3800 WOT studder

[pumacorp]

I have a 93 bonneville motor with a sc and it runs real fast when I 1st start it,,but after 2 quick runs it all of a sudden starts to lose power and studder..
Now if I shut it off for 10 min and get back in im good for 1 more run again thats fast ,,then she studders and even sometimes back fires a little...

Any ideas??I got a code 26,,,quad driver circuit 1 code,,but Im almost sure thats the evap control valve thats missing...
No vacuum leaks,,,fule pressure is at 40 psi plugs and wires are good..
TPS sensor is at .37 and idle amd 4.1 at WOT....So wasnt sure if the TPS might be causing this cause if im not mistaken im supposed to run at 5v at WOT...

Any ideas?

[Jrs3800]

Fuel pressure should be 41-47 PSI.... You need to check that very close..

You could also have KR( Knock Retard ).... You need to get a Scan tool and scan for that...

If you run lean, and or have massive KR you will pop a piston in due time

[pumacorp]

Fuel pressure was actually the 1st thing I checked and it was 40 and rise on throttle like it supposed to...As far as KR,,,very hard to tell because I sold my shop and the Modis went with the deal..

Its been so long since I worked on an OB1 can u even scan for that on that old system???

[Jrs3800]

Yes you can scan on KR on a 93... KR on these is a bad thing.. When the PCM sees the KR it will pull timing to try and avoid the KR... As you know when it does this you will drop horses..

As well are you on the stock Pulley?

Have you checked the Manis for cracks( The tubulars love to crack )

[pumacorp]

What is a Manis???I dont have alot of experience with superchargers and have no idea what a manis is lol..
I do get 2 pretty good runs and then the 3/4 to OWT studder starts..It goes away if I bring her to 1/2 throttle..
Stock pulley also getting a code 26 which is circuit 1 quad,,,which one of the things it controls is a boost solenoid,,could that be the problem?

[Jrs3800]

I was wondering if you had ever checked the Exhaust Manifolds for Cracks.. They like to crack on the 92-95's with the 3800 Series I which had the Tubular Manifolds..

If the Quad driver problem has the Boost control solenoid on the same Circuit than yes that could be a problem...

[pumacorp]

Again thank you for your time...I havent found any cracks..I did how ever bypass the BCS a few days ago and it seemed to be ok...So im guessing
either BCS is bad or the computer is bad and giving the wrong pulses to the BCS..
In any event I have ordered the BCS and a new computer..The new computer was ordered cause I know these old computers in this yr had lots of failures anyway..I got a delco computer in sealed package from ebay for 50.00 so i couldnt pass that deal up anyway..

Do u happen to know the parameters for the tps???I am getting a rough idle and wanted to see if the tps is on target..
Was also thinking rough idle could be the BCS leaking or malfunctioning and causing boost to run at idle a bit..

Any input would be grateful..

[Jrs3800]

Off the top of my head I think the TPS should be .36-.42v at Closed Throttle( Idle )

Generally those PCM's were not that bad... But for the price you paid for an AC Delco unit, I would have bought it too.. Its very possible that the Boost solenoid could be causing the issues you have..

Let us know how it all works out..

[pumacorp]

Yeah I will for sure...
Thats shipping included 40.00 for the unit..I just couldnt pass that deal up..
Besides the quad 26 code can be the computer as well..If it wasnt bad it is bad now that BCS was shorting burned out that quad in the computer..

Who knows ill find out soon and the TPS is on target...

Having TCS issues now,,thats also on quad circuit 1 if im not mistaken...
Hoping thats the computer just failing in that whole area..
I have the engine in a fiero kit car so im not looking foward to working on this at all ,,,theres no room at all...