Do you have a data logger to monitor what's going on when it stumbles? Also, do you know what the check engine light is on for? That may be the issue. With blow through setups, there's no need to recirculate the air back into the intake. It's been a little while since I dealt with forced induction so, I may be missing something. Hopefully, someone else can offer more help.

 

oh im sure the mil light has to do with all of it. when i start it, it idle rough for about 3 to 5 second then the light illuminates, it was close to about a minute later and the idle bumps up to about 1000 rpm, settles to 900, but smooths out. anytime before that, i have no throttle response it affects nothing, just bogs. if i wack the throttle, it just falls on its face,pops in intake, i need to get the scanner tomorrow, i guess i can just use a 95 camaro program right? since its a obd1 with an obd2 port? i have new ignition components and new ngk 6's with less than .030 gap. thanks for the help, i will let you know!!

 

ok guys, here it is, scanned it and got a code 43 (esc module, circuit) again its a complete obd1 conversion, all internal to pcm, tach generator, knock sensors and all, i may need to check the module and make sure it didnt come loose from shipping. thnx agian! how's it look?

 

well opened pcm, no knock module!! so installed the one from my obd2 computer, and still no joy!! runs rough same 43 code, until o2's go into closed loop then it smooths out, but no quick throttle response!! i can slowly bring the throttle up, but whack it and it just lays down. wtf! started to think i should have left it all alone. the snapon scanner showed anywhere from 9 to 13 on the knock sensor(not sure if thats volts or what) o2's seems to be slow on heat up and cycling, not as smooth cycling as i remember on autotap with the ls1. hope to hear from you guys

 

With ignition on, disconnect both knock sensors on the block and put a meter to ground on them one at a time on the voltage scale, what do you read? If they are both great than 5.5 volts you are going to have to measure the output of the PCM on the pin I stated above.

If they are both 5 volts:

-measure resistance on knock sensor to ground, should be 3300-4500 ohms, if they do then it is a wiring connection problem at the sensors or something like that, if not you have a faulty knock sensor.

If 0 volts:

-wire from PCM is shorted out or open somewhere in between.


Post up what you get from this, I would hope that you find something with the above checks.

Also I thought that there was something with this circuit that had to be done internally to the PCM when doing an OBD1 conversion, I could be mistaken, but it sounds familar.,

 

hope to have the weather and time to get the resistance and voltage checks done tomorrow, but i do have a question, how is that system related to the o2 sensor going to closed loop and smoothing out, is that a function of a "limp mode" type deal?

 

Mine had the same problem. I installed the supercharger with a stock tune and started the engine. The engine was 100% stock at the time. It was missing and popping. I hooked up my laptop and used a tune from PCMforless. It fixed the problem. Maybe contact pcmforless?

 

. I hooked up my laptop and used a tune from PCMforless. It fixed the problem. Maybe contact pcmforless?

Yeah looks like I may have to get ahold of Bryan and see what he thinks

 

Take the belt off and run the motor, does the problem go away? It sounds like a tune issue.

I'm just not a fan of box tunning for this kind of stuff. Think of the money you spent to get this far and the power and drivability will all depend on the tuneup in the motor and in the computer. Go to someone that has done a OBD supercharger before and you will be happy with what you end up with.

Good luck.

 

I'm just not a fan of box tunning for this kind of stuff...

+1 You will want a good tune- not only for performance but also for reliability. I used the PCMforless tune to get the car drivable then took it for a dyno tune.

 

well, checked out the knock system, not all that good, both sensors read open!! made sure had good ground, read ground to the frame and was good, but from sensor chassis to terminal, nothing!! also, key on, power on right side was 4.78 volts and left side 5.3 millivolts! (nothing!) read wire to pcm and checked both good.looks like i may just have to tune out the code 43 if no power coming from pcm right? also if the conversion was done inside the pcm i should see the tell tale resistors right? just trying to plan for possibly getting new ks, whether older or newer.

 

thanks for all the help, found a couple discrepancies, like i said earlier, knock sensors were very tired, all read out of range, but the big one was the pcm, the obd1 conversion was performed and i was told by last owner the knock sensor did not need to be replaced with obd1 types. with my problems i opened the pcm and found no resistors on the signals for the knock sensors! its narrowed down now, i will let you all know how it goes when i get the sensors installed! thnx again!

 

well its running, no light. looked like it was going to be a pcm. but what i didnt know till after researching was with an obd1 computer and with obd1 knock sensors pins 21 and 22 still had to be bridged. soldered a wire loop in and done!! still cant whack the throttle yet but hope its still learning. thnx guys!!

 

Wut kind of fuel system? U may also be running lean.

 

well figured it out, obd1 conversion was not complete. not knock resistors installed. changed knock sensors to obd1, and still no good, found pins 21, and 22 not bridged, bridged them and it seems to be learning good now. but notice its idling high, posted about it but the opti vent is not metered by the design, trying to figure that out now. thnx