once again I will repeat that these are ls6 injectors not the ls1 like I had said before, they flow 32 lb/hr@ 58 psi, 28@43.5psi here is the racetronix page selling them:

http://www.racetronix.com/12561462RFM.html

besides if I had my injector constant was set too high I would not be getting the strange things I am. I really think my injectors are screwed up and some are going static. when I first fire the car I can't make the rpms do really anything when I pull wires, it just runs crappy. as soon as the car runs for a minute or two, pulling some of the injector wires makes the car rev up. this points to some sort of combustion or something going on in that cylinder even though fuel should have been removed.
with fuel removed from a cylinder I should now have a "dead weight" swinging on the crank and pressure building when the piston comes up, like an engine break. this is the science of a piston internal combustion engine (I knew I sat through those thermodynamic courses for something). since there is no combustion in that chamber to help push the piston back down the rpms should drop a little because the computer only sends a signal for the injectors to pulse. the computer has no idea the signal is not getting there so it doesn't compensate for the loss of the injector. at least 4 out of the 8 cause a drop in rpm when you pull the wire.
after looking through this harness thing I am really starting to lean towards crapped out injectors. taking it apart and putting it back together has changed nothing. there are no leaks that can be found, and believe me he have hosed this thing with propane inside and out. if there was a leak we would have found it.
this is a problem that has been there since day one of firing the new setup and before the swap the car ran better than any stock tbi car I have seen. all other alternatives have been eliminated now except for bad wiring or stuck injectors. after the investigation of the grounds on the new harness and the injector terminals on it I really have to think injectors is my problem.
now that I come to think of it, when we pulled the wires before we tore it down and put it back together it was different cylinders with the rpms increasing when the wire was removed. this just has to be the problem.

 

new stuff: well replaced the injectors with some svo's. vaccum came up an inch or two. the weird thing is that fuel pressure now holds when I turn the key to on. before when I did this test, the pressure went to 44-48psi, then as soon as the pump stopped running the pressure dropped out to zero. now, the pressure jumps up to 44-48psi then holds at 44 psi. also the whooshing sound that it made when the pump ran went away. so the some of the injectors must have been leaking, but that wasn't the main problem. now what?

 

how is the oil? does it smell like gas?
now you can start going back over the other things again, hopefully something will turn up this time.

 

Post back from hell :-)

Please read entire post before responding to insure it hasnt been done already

thanks

Im pushing this post back up for Curtis 1992rs/ss. Called me today and wherever he had it carted off to basically cant fix it either. So we are looking for suggestions and ideas here and yet more ways to eliminate things we have already tried.

thanks
Jeremy

 

This thing is really turning into a hell of an experience.
Seems like verything is right yet, it's not!

Maybe try a different bin just to see if there is an issue with the code you are using? you may have already done that.

Other than that, it leaves only the adapter.
Get it out of the injector equation is the only thing I can think to do except recheck the timing and wires for the 100th time.

 

we actually swapped out the ecm and the memcal for an unopened 730 ecm with a 350 memcl in it. granted running with a 350 memcal would make it run rough as well but there should be a change in it's characteristics. it did exactly the same thing. that is why I will completely rule out computer error here.

 

This is gonna sound stupid, but it is the only thing I haven't heard mentioned, and that is spark. This thing is actually firing on all cylinders with a spark tester, or is it passing fuel instead of gas? Like I said, it may sound stupid...

 

The only part I see here, that has not been tested to within an inch of its life, is the adapter box. This strikes me as the number one suspect for inducing problems.

Would spring for a tpi harness, as you already seem to have everything else, be over the top? After all, how much time do you folks have invested in this now? How much money is your time worth??

 

I'm assuming Curtis got his car back, I'm not sure if he swapped in my MSD distrib yet or not, he was going to try it.

Pin testing the harness is a complicated PIA with that damned adapter box harness crap.

We used TPI on the engine side and TBI on the adapter side, what a PIA it was, couldnt find anything obvious wrong doing it that way either. Even tested all the wierd stuff like Rbob and a 2 hr conversation on the phone with Vader suggested.

I hate to blame it on that harness/adapter but I'm almost thinking its the onlyn thign we cant truly rule out at this point.

If anybody has a spare SD or painless SD harness we could use for a day to plug in and test we would greatly appreicate it.(assuming u dont need it for your car at the time:-))

later
Jeremy

 

There's a thread on here to repin the TBI harness to TPI harness. Several ppl have done it successfully.

There's a chart and it's basically a plug n chug (probably be simple compared to all the work you've done so far.) This would also be a chance to ohm out every wire (i know = pita).

It's not hard and would eliminate the conversion box which I agree sounds like it could be a source of problem.


Also: I would do a compression test (maybe you already have) on all cylinders.

The L03 has a TINY Cam/Heads compared to the LB9. Maybe whatever chip you have needs some major tuning. Could be flooding out cylinders on startup - how do the plugs look?

Just shooting in the dark... Good Luck!

 

When you swapped over the intake any chance you used that cheap silicone that peirces your nose when you smell it (like vineger).
You have to use a silcone that is "sensor safe" It will contaminate your o2 and your oil!
Just a shot as I am fighting my own vac. problem on my TPI!
Good luck!
TPITEN

 

I used the good black stuff. all the sensors are reading correctly. I am back at school in iowa so the car is now being worked on at a shop. the guy working on it sent the computer data back to S&P, they looked at it and think that a resistor needed to be inserted into the injector wire feed (sounds like S&P might have screwed up in making their box). when I hear what that does I will let you know.

 

Does the box supply a shared ground for the injector drivers?

When you do a TBI to TPI swap, the '730 requires two grounds for the injector drivers, where the '746 used the ECM ground. Could be a potential problem.

-- Joe

 

Got a link to the post about repinning the TBI harness to TPI?

 

Hes got the best looking car I love to hate :-)

That damned conversion box was a PIA. Ever try tracing wires using the factory books and using one side for TPI and the other side it TBI ugggh. lol

Hey Curtis send me a PM on the update on where you are at with it

later
Jeremy

 

Yes. We'd all like to know the outcome of this nightmare.

 

well the car has been at this shop for quite a while. since the cost to tow it back to my house was about the same as having them put in the painless harness I bought a painless harness and told them to go to town. luckily I will get my money back from S&P so that will cover all of the cost for the painless harness and installation plus get a few dollars back. supposed to know by wed. what the deal is.

 

If its that damned converter harness I will be very happy.

So will Vader , then we wont have to drag him out here too :-) lol

Did S*P tell u anything else about it or ahvent u talked to them?

later
Jeremy

 

*** I hope it was that stupid box. I only called S&P to see about a refund, which they will give me. otherwise we might have one of the hardest problems to find that I have seen on the board

 

When you guys figure this problem out -- Lemme know what it was. It sounds exactly like what my truck is doing, cept I cannot get it to run long enough to do anything with the engine.

I did some very in-depth testing on my 355, and I'm at a total loss as well. I checked every single part of the ignition system and fuel system, and I cannot find anything that is wrong anywhere. The truck is running very rich, and shakes like crazy at an "idle" of 1000 rpm if I play with the throttle to keep it working.

I've got between 140 and 150 PSI on every cylinder (typical for the lower compression 80 model engine I have my TPI on) It ran like a top with the carb, and regular HEI, so that kinda rules out any problems with the engine mechanically.

I came to the same conclusion that it may be my injectors going static, and I'm waiting on a new set to get here to try it out.

Just makes no real sense though, cause the engine will only "run" if I set the timing to nearly 50 degrees BTDC (according to my timing light, if I set the dial to 50 degrees, the timing mark appears on 0, timing mark is accurate, tested it by watching the operation of my valves, and with a feeler in the spark plug hole, right after 0 on the timing tab, the engine starts to bring the piston down, and the valves begin to operate right when they should)

If I set my timing to about 0 degrees, it should be able to start if it it getting fuel from the ECM, but it only kinda sputters like the only fuel it is getting is from the cold start injector (unplugging it causes the engine to just crank, no sputtering while it is hooked up) yet my noid light tells me that the ECM is pulsing all of the cylinders.

Makes no real sense to me, and is extremely frusterating. I've been trying to make this thing work for months already, with no avail. I think I've checked and replaced about everything on this system, right down to checking all of the wires for continuity / possible shorts etc with absolutely no results. I've saturated that engine with propane, and the only time the RPMs ever go up is if I stick it in the end of the MAF, lol

I just had my injectors tested too, and the guy said they are fine, but "cut out" at 45 PSI, so I assume he meant they go static at that pressure. I've got 42 PSI in the rail, and it only drops down to 39 PSI after 2 minutes of sitting after the pump is shut off.

Basically, I've tested absolutely everything, and I cannot get the engine to do anything more than just sputter at 0 degrees advance.

 

So, where are we with the project?

 

Well,

I asked Curtis to call me a few times and give u a thank you too, but I havent heard from him.

Last post I know, the car is running and yes there was something wrong with the adapter harness for the TBI to TPI conversion.

Car is now running using a complete TPI painless harness without dumb adapters and the like.

So apparently, the problem was indeed in the adpater box/harness for TBI to TPI.

I'm happy I figured out what it was/heavily was leaning towards, just never found someone with a harness to jumper and test with in the car.

later
Jeremy

 

well 5 months, new harness and a lot of aggrevation this car is finally back in my garage and guess what. nothing has changed. car still won't idle and barely able to start it. not sure what to do now.

 

to bad you live way up there, i almost certainly could find the problem if you lived down here.

do you still have liquid gas coming out the tail pipes?

does the pickup coil in the distributor still have the plastic sleeve on the connector where it plugs onto the module?

 

Well I'm imagining the system is running directly as a 730 setup now.
This is now a straight TPI setup without the adapter questions/issues so I'm sure we can get to the bottom of this.
Can you give us a new run through on the current symptoms so its clear.
If nothing has changed then it could be something with the motor to chassis ground. Try running a datalog while you install a jumper cable from the engine to the battery negative post.
See if readings rise.

from what I see,
Injectors changed,
Fuel psi is good,
Timing confirmed,
New ECM/memcal,
New harness,
power is good,
the best plan is to begin again with going back to basics and do a good check on every sensor reading to be sure they respond properly.

 

are you thinking the pickup coil is plugged in backwards at the module?
I've read that it could be triggering off the wrong side (rising side not falling side) of the pickup if that is done. Not 100% on that but do know it can cause issues.

 

i rember gmhtp did a article on a thirdgen with a tpi and it was called get those grembalins out of ur tuned port they had some simular probles with there tpi and it was all linked back to a inline fuse that is located on the passanger side by the rad support it looks like a verry skinnie relay but its a fuse with a case over it its for the f/p but for some reason when gm high tech's blew it made it idle righ and stuff its a little bit of a crack shot but hey what else do u have to loose

 

Oh, NO! It's Baa-aack....

Same symptoms? Looks like I'll need to summarize what has been done and the mods list so I can wrap my little mind around all of it.

Working....

 

JP86SS, its something im wondering about.
i have had a few GMs that had some strange problems, from a no start with spark & injector pulse, missing & back firing, up to an intermittent low performance & that's what it turned out to
be.

i can remember 2 that had new pickup coils that had the wires backwards in the connector, one of them i know was a new Delco pick as i had just put it in & it was wrong from the factory.

 

jeremy


has the fuel pump been changed in the tank. a tbi works on a much lower psi than a tpi with about the same amount to flow #'S

had a problem with my maro running rich out of the blue and it turned out the fuel pump was dropping the pressure low enuff for the fuel not to spray into the port. it kinda pissed a stream and it caused a rich condition. till the ecm tried to pull fuel out of it and then it all went to hell.

the car run fine until it got into closed loop. hell and to top it all off the tach was shorting the dist/module out after driving the car for a short while. sound like you guys have had about as much fun with that one as i have with mine little basket case.

and to think i got a bargain @ 1k with a blowed head gasket. it has been a mess tring to undo someone's mistakes.



food for thought.: thumbsup:

 

lol

Curtis(a992 rs/ss) and I talked for about an hr the other day.

We cant do alot since hes in school.

We have a couple ideas and the like, but I want to burn it as much as he does now lol

It will live dammit this I swear.

Vader/Jeff, look for another 3 hr phone call when he lets me know when he will be home from school lol

Curtis or I will keep it updated as info becomes available.

later
Jeremy

 

anything come of this????

 

Not yet, but the second semester will be over soon enough, and we'll be back at it, I'm sure.

 

This was a very interesting thread, I'm just wondering what became of it. Did you ever find the problem?

 

Long story of which I wasnt involved in.

He has the car.

It has been rewired for the engine a second time.

Found the accell base serioulsy warped.

Further testing impossible due to OL readings on the pickup coil.

Will advise further when parts replaced and we have more to comment on.

later
Jeremy

 

when the pickup coil gets replaced, let him know to be sure to use a A/C Delco. they really are better than what the aftermaket has to offer.
also, he needs to make sure the reluctor is in good condition, with no chips or cracks on it.

 

I'm interested in an update. I've got an 89 350TPI Formula ( all stock,) that I just rebuilt the longblock on and although it runs good, I'm only pulling 15-16" of vacuum at idle, with a stock cam, ( 650 RPM.) The vacuum also slowly fluctuates as though it has a rich/lean problem ( I'm use to that type of movement from tuning carb idle circuits.) I've gone through vacuum diagnosis and the engine tests out mechanically, even though I can't find a pinpointable intake leak, I'm leaning towards re-doing the lower intake gaskets.

Fuel psi static is 43psi, and running is at 37 psi, it was about 42psi running but I tweaked the FPR housing.

The BLM is still at 108 so the ECM thinks it's rich ( O2 is new/operates fine, good crosscounts,) and all other sensors are operating properly.

Timing is set stock and increasing it does not have a great effect on vacuum.

The injectors are original ( as far as I can tell,) and were cleaned/flowed/tested at Kinslers. All were "good"

My fuel pressure does leak down after a little bit, I have not isolated a problem with injectors or the drainback valve in the fuel pump assm.

Pulling injectors while running seems inconclusive, not any one injector seems to effect the idle quality any more than the others. They all make the engine run a little rougher.

Q: What brand/number intake gaskets does everyone like for a stock plenum?

Q: I'm not too familiar with these TPI engines, was their a problem with the stock roller cams wearing out, etc.?

Thanks, Rob