ok gurus of the TPI world lend me some help. Just swapped a TPI 327 into my 94 Toyota pickup truck. Now problem I have is it will only idle decently when the IAC and MAF are disconnected. Put MAF on - it dies, hook up IAC and it slowly dies. No error codes whatsoever besides when I don't have the MAF hooked up, don't get a code for the IAC even if it's not connected. I can barely keep it running with MAF and IAC hooked up but I have to dance on the throttle. Here's the engine specs/technical stuff.

TPI:
Intake-1989 w/ no 9th Injector
ECU-1227165
Prom-APYM (dealorship says same as Prom 16133467)
Harness-Painless 60202
Vats-Painless module
Fuel Pressure-42 psi
305 stock 19 lb injectors

Engine:
68 327 Block .030 over
Cam-Comp Extreme Energy rpm 1200-5200
Compression: 9.5:1-10:1
Short Tube headers

So far troubleshooting this thing have replaced Knock Sensor, MAF Power Relay, Temp Sensor, ESC, Fuel pressure regulator, and cleaned the fuel rails. Any help would be greatly appreciated.

 

heres a pic

 

Starting to think faulty maf due to as soon as air starts going through maf motor dies. Anyway to test the MAF? Don't really have the 162 dollars to buy a new one at Autozone.

 

wont let me edit and add the complete cam specs so here they are
Comp Extreme Energy part # 12-256-4 Dur @ 50 212/218 Lift 449/456 Lobe Sep 112

 

I'd start simpler. Hows the timing, did you set it the right way? Doublecheck your wiring?

 

Base Timing is set at 15 degrees. Without the MAF hooked up runs like a champ. Even drove it today to the parts store.

 

I may be offbase here, but are 19 lb injectors large enough for that motor? Also - is that chip for the 305 injectors or the 350 ones?

 

Could have went either way with the injectors. But went with what I had. Prom is for a 305. Code I'm getting is 33 MAF pressure sensor (high) when I keep it running by hopping on the throttle. More I think about it coming up with 2 possibilities first the MAF sensor second being maybe the change in displacement isn't making the computer happy. Wish I could find a way to test the MAF.

 

15* base timing?? Isn't it supposed to be about 8* or something??

Doesn't sound like that is the CAUSE of your problem, but that is way off from what I know.

When my MAF was bad it threw a code 33. I followed the troubleshooting flowchart for code 33 and it proved the MAF was bad. My vehicle ran with a bad MAF.

Running off of a '165 305 PROM/350 injectors. No problems with a good MAF. 355, '87-88 TPI, Vortec heads, SDPC base, roller cam, headers.

BTW, my cam runs a 112* centerline cam and that doesn't cause any problems, or if there are problems with it, small enough to be little more than barely noticeable. My duration is only 204/214 though.

 

Base timing for a TPI motor with a stock prom should be at 6*BTDC.

You're going to have issues no matter what you do when a 112*LSA cam on a tune designed for a smaller displacement, lower compression, and about 117*LSA. You'll be getting a lot more overlap at idle, which will throw the MAF readings off, and cause fueling issues. The compression and displacement changes will also cause fueling issues. It should run better than what you describe, but it'll never run RIGHT without prom tuning.

Also the stock TPI injectors are notoriously cruddy.

 

To test the maf sensor(assuming it will run with it connected) you can tap it with a screwdriver handle, if the motor starts to bog and or die bad maf.

 

Swapped out the MAF yesterday and it was night and day. MAF was totally shot. Dropped the timing down to 10 degrees. She runs a helluva lot better now. Drove it today and she only stalled out once (course it was a decent sized mud puddle). Very happy with the power this motor is putting out, got enough power to turn 36" Swampers. I agree that the PROM is going to need to be tuned to get the best results. I'm just starting to scratch my head on the code 33 though. Thinking it could be due to the displacment increase. 305 only has soo much vaccum so starting to think that if I use a 350 PROM it might remedy that but issue there is I'll have a conflict with the injector size difference.

 

If you swap to a 350 PROM, just run the 350 injectors.

I've got the 350 injectors running on the 305 PROM, but since the injector flow is going to be greater, you will get more flow even though the PROM is set for 305...think about that. The time the injector is open is no different, but the amount of fuel that is "shot" is going to be greater.

IIRC from posts here, code 33 is often blamed on the PROM settings for idle air being too little for increased engine breathing. Someone responded back to me that changing that parameter in the PROM fixed their code 33. I can't say it won't, but my engine, which is quite a bit different than a 305, flows nowhere near enough at idle to trigger a code 33 according to GM specs.

 

After I clear the codes at idle it dont trigger the code 33, after clearing the codes a few times finding out it shows up between 1500-1800 rpm. If I can get it over 2k rpm w/out throwing the code I can run all day at or above 2k rpm and it wont throw the code. Issue now is trying to either come up with the money to buy the stuff I need to burn/tune PROMs or find someone in my area that can help me with it. If I have a professional "PROM burning company" do it then it'd cost more than getting the stuff and do it myself.
BOB