I`m not much help on this subject, but I know a little on TPI. I think your assumption is right, you have too much cam and airflow mods for a TPI, I would think your combo would have to be placed on a computer where a Chip could be customized to your engine. I`ve heard lots that FI systems don`t like big cams, especially the size your running, I`m sure someone else on the board can be more help than I am, so I leave this open to opinion.

 

thats exactly what i was thinking, so do you wanna buy a tpi setup....lol, thanks for the help but if anyone really does now anything about tpi, or any comment at all im here, thanks again

 

Is it a mass air flow or speed density tpi setup?
Any extra info you could give would be great.

 

I think your setup will work fine with the TPI, but what are the specifics on it.

As stated above large cams dont get along real well with oe computer setups. The problem comes down to a lack of manifold vacuum with large cams. However, your is not really large enough to cause bad problems I dont think. I am betting you need a custom chip for that cam profile.

I am running a 525 lift 250 duration cam and just got the engine started with my edelbrock system. It only idles at 10 inches of vacuum, but still runs perfectly even though it is a little fat at idle. I have not been able to actually drive yet, but no idle problems at all. I bring this up to let you know I think there is hope if you get the chip right.

I would check and make sure there is no trash in the fuel sytem causing the injectors to stick. Just an idea.

Chris

 

the truck is speed density and the chip was custom burnt by motorvation, they have all my cam specs. injector sizes and every other little detail about my engine, they say that my problem is not the chip, i appreciate you guys trying to help, you actually seem interested, ill find the pics of the motor and attach them later so you can check it out, any more help would be appreciated

 

If i was reading this right you have the ignition timing set a 0 degrees? is the timing controlled by the computer at idle? if not set your timing to 36 at or around 3000rpm.


I got this wrong i thought you had changed out to a carb not computer controlled.

 

i noticed you said it was skipping at all speeds can it be pinpointed to any particular cyls. also fuel pressure seems a little high for idle (is it adjustable)try more like 30-35psi. theres a vacume fuel pressure regulator on most tpi systems it should not read that high till w.o.t. and 45 is usually about the max. the lack of vacume may be creating problems there. is this an oem fuel system and computer just with prom and wiring mods and if so about what year. it makes a difference in the year for some of the setups, like base ign timing a lot of them need more like 6-8 deg, tps should be around .60 - .70 volts , when setting fuel pressure you really need a scanner to be able to read the ecm, your looking for injector pulse withs, there read out in miliaseconds, around 1.5 m/s at idle give or take is close to the range , you will probably have to play with it some(fine tune it) but this is a good place to start. everyone turns the fuel pressure up trying to compensate for lean conditions only to find that it usually complicates the problems, having the right prom and injectors is a good start. and if your running the stock intake, plenium and runners, your gona find them a little limiting on the high side. hope this was a little help for ya good luck mikey

 

you disconnect the timing advanced which is a little brown wire that unplugs in the cars harness between where it plugs into the computer and where it drops its first wires from the harness, usually under the hood but sometimes undser the dash, on an older injection system and set the timing to its spec. which i was told was 0 degrees, the setup is for a 1991 camaro the computer and chip are new...the stock chip is a 1991 camaroz28 350 with no vehicle anti theft(vats). the motorvation chip piggybacks the stock chip kinda like a jet performance chip..if there is another timing setting then i was told wrong, although ive tried turning the distributor both ways and it didnt seem to make a difference, i believe it was when i advanced it probably 8 degrees it was starting to come around and idol but it skips like crazy, ive tried to pin point it to a cylinder but you cant thats why i think it may be more than one.. i think im almost stuck on vaccuum leak or fuel, i will definetely change the fuel pressure down and try from there to get a tech 1 and start checking all the sensors, map sensor, knock sensor etc....i set the tps correctly by the painless wiring hand book, and thouroughly read it many times to make sure i didnt miss something, i will get back with some results this weekend, but keep the info coming i appreciate it

 

according to my info, factory 1991 tpi 5.7s are 6 deg. btc. even 5.0 tpi is 6 , only the tbi 5.0s are 0, i think id try 6 btc. to start 92s went to 8 btc it realy depends on the timing curve programed into the proms , usually they dont change the overall curve unless nessessary they do have it come in a little sooner or later sometimes, the biggest thing they mess with is usually the fuel maping, espically with speed density systems. you may have to play with it a little but 6 btc would be a good place to start. and yes a brown wire with a white or tan stripe is usually the right timing connector to unplug when setting timing. if the plugs are sooty or wet all eight of them its probably a rich fuel condition.

 

Welcome to the "TPI omygo* what have I gotten myself into club". I too have a TPI. When you say it skips Do you mean it misses a cylinder or surges, does it backfire? I crossed the magnetic pick up wires on my MSD 6 and it caused it to back fire at rpm's over 2500 and I missed one vacuum port that made for an erratic idle. Good luck.

Welcome to the "TPI omygo* what have I gotten myself into club". I too have a TPI. When you say it skips Do you mean it misses a cylinder or surges, does it backfire? I crossed the magnetic pick up wires on my MSD 6 and it caused it to back fire at rpm's over 2500 and I missed one vacuum port that made for an erratic idle. Good luck.

 

does it run cruddy when its cold?

 

Does this system use a MAP sensor if so you can use a hand held vacuum pump with the Gage and fake out the map , pump it up to about 18 " of vacuum and start it up and see how it runs at idle Do Not Rev it . you may not have enough manifold vacuum with the cam you are running .

 

ive been workin to much and havent been able to hit the garage ill def. check it out this week, if it comes down to having to change the injectors im buyin an intake and carb to make me smile, probably be faster with the carb.?what do u think....

 

did you ever get the tpi system up and runin or did you give up and carb it i also did a tpi swap on my s10 bored 60 over cam head work painless wirring 92 compter i did the swap my self and im 17teen there was a munch of times were i just wish i had when with old school carb but no i wanted tpi for daily driver the only thing i had to do was raze my idel up runs like a top mine would not idel intel than if you lookin to make crazy power go with a carb if you like a daily driver tpi is the way to go

 

I sure hope he got it right, after all this thread is 5 years old.