i did a TPI swap on my 91 Caprice, and still have some problems - i heard on a other forum that you guys here a really good with that stuff, so heres my situation:


what i have: it's a TPI from a 85 305 camaro (it had the old 1226870 ECM with external MAF controller); i changed to the 1227165 ECM to eliminate the old MAF controller. I have a 7165 ECM with a PROM from a 89 350 Trans Am - cause this car has VATS, i made a new PROM (i edited the BIN with Tunercat) with disabled VATS, disabled the EGR diagnostic (the car has no EGR system cause i'm here in germany and the US emission controls are useless here) and set the injector flow rate to 19 pph - since the cold start enrichment is included in the calibration at the 89 cars, i disconnected the cold start injector. the engine itself was a 91 350 TBI engine. I'm using a painless wiring harness.

the problem: after a cold start, the engine dies shortly after starting (about 4 seconds) - i can hold it running with the acc pedal, but at WOT theres no more fuel delivery (no injector firing, tested with noid light) - when the engine is warm, it idles by itself (without help from the acc pedal), but it still runs very rough, and not like a TPI should run, and it still dies every now and then. Sometimes it runs too lean, sometims to rich.

i checked the fuel pressure, it's ok at 41 psi

for troubleshooting i made a PROM from a 87 350 Camaro and re-connected the cold start injector. with that, the engine is running a little bit better, but still dies sometimes, and always runs very rough

WinALDL shows me no error codes and the sonsor values for MAF, Coolant and TPS seems to be right

since my test with the 87 prom brought a little difference, i guess the solution for this problem is in the PROM - but i don't know where to start

any help is appreciated

 

okay, i'm just trying to understand the tables in tunercat - i already got how the closed loop and the MAF works, but, what i still don't understand is the "BPW Fuel Vs. Load (msec)" Table

what dosen't makes sense to me is, why the ECM needs a value for the opening time of the injectors? i mean, it calculates this time based on the MAF value and later corrects the time using the O² value, right?

i saw that the 87 and the 89 PROMs have some differences in this table

so, maybe anyone could explain me the correct usage of this table?

 

Second sticky down from the top, Chapter 5, 165, first link.

RBob.

 

"sorry, i'm unkown with the airport - request progressive taxiing"

 

theres still one thing that i can't understand: why is the engine running so bad with a stock prom? i mean, it's a stock engine (ok, it was a TBI engine, but the differences to a TPI engine shouldn't be so massive? and if i run a 305 TPI with stock 305 prom on a 350 engine, it should also run, or not?)

 

Click on this link then follow to chapter 5:

https://www.thirdgen.org/techbb2/sho...hreadid=288763

RBob.

 

Many items are different between the two engines. Heads, cam, exhaust, induction are the major ones. There may also be other problems: fuel pressure, ignition system, drivetrain loading. There is really too much for anyone remote from your situation to give anything but guesses. That's the problem.

RBob.

 

THanks RBob

yes i know there are differences, but they are not too far away from the original TPI engine - and this is why i choose a MAF system, not a speed density. i thought the MAF system should run acceptable on this engine without bigger mods.

okay, i will read the articles now and think what i will do next...

 

okay, i read the article and tried a bit at the car with tunercat and the romulator

but: how can changes in the table take effect, as long as the engine is running in closed loop? every time i changed the PW for one or more LV's, it seems to take no effect - as you can see in my screenshots the PW in WinALDL is always something about 2.5 - even if i set a much lower or higher value in the BPW table

here i have two screenshots from WinALDL:

here are the INT and BLM values far away from 128:


why are here the INT and BLM values both at 128, but at the same O² voltage as in the previous pic?


in closed loop the engine is not running perfect, but its okay - what i still didn't find with the search engine here (i'm sure, anywhere in this forum it is ) is a equation, which i can use to calculate the correct entry for the BPW table using the BLM and INT value - i mean, if the engine can run good in closed loop, i only need to take the values which it's working with in closed loop and enter them in the table, or i'm here on the wrong track with that?


btw a little other question: why is it running always at something about 1000 rpm, if in the "desired idle speed" table it's set to 550 rpm? or will this matter automatically be solved when i have a correct BPW table?

 

Can't help on the MAF stuff but the desired idle speed is for "in gear" (at least on the SD)
I found that out when emulating looking for a result.

 

i will try this - but in the currently situation the engine mostly dies when i put i in D

 

I had a strange poor running situation when I first started burning proms. It was the zif adapter but any poor conection from the chip to ecm can cause weird stuff. Somtimes it would throw a code 41 but not always. It idle rich and when I drove it would stumble and I almost blew the mufflers off with the backfiring. I know certain years of tpi had diferent mem cals, but if you have used a zif or a adapter or solder double check all of it. This problem I had was like a demond it would come and go, my starter has seen Its half life in the last couple of months. Wiggling does not show the connection. I understand this only now after looking at the pins of a zif how lose they are when the lever is thrown in the lock possition. The pins have little or no resestance in the socket.
Somthing for me that help indetify the problem was to remove the chip all together and run off the resistor pack. It ran better because when the chip was in and had a poor conection the ecm kept adjusting for the missing bin information. This may be why your changes don't take place. Good luck

 

Did you remember to remove the stock TBI knock sensor, or did you re-use it?

I had a similar problem once, turned out to be a faulty oil pressure sensor. The ECM was not receiving any oil pressure reading (or maybe in you're case, a struggling sensor thats on it's way out), which resulted in cutting off voltage to the fuel pump...

This sounds like you're ignition. You'd be surprised what a set of incorrectly 'gapped' spark plugs can do to a Tuned Port Injected engine. Either this, or you're ignition module is fried...

 

i used the one from the TBI - but including the TBI ESC module - why? aren't they interchangeable?

that i checked - the fuel pump is getting good 12V


that was my first hunch - the ignition system is complete new - new distributor, new spark plugs, new cables, i even tried three different EST modules from running cars


i just ordered 24 pph injectors, cause i want to bring the engine as near as possible to a stock configuration, maybe i will have a chance to start with a stock prom from a 350 car

 

I don't believe that they are, but then again.... I never swapped from TBI to TPI, so I'm not 100% sure. If anything, I would imagine that the only thing interchangable between both systems would be the Fuel Pump Relay.

When swapping from a 305 TBI, over to a 350 TBI... you have to swap knock sensors (and that's when using the same injection system), so I'd imagine you would need a TPI knock sensor (and O2 sensor, if you retained the TBI's) in it's place....

Yes, for the first 4 seconds (which is about how long the oil pressure sensor activates fuel prime. Their wired together), then when the ECM senses no oil pressure (after 3-4 seconds), it cut's the fuel pump's feed.

This is common when the car will start, run for 4-5 seconds, then die...

Try installing a TPI ESC module, and toss the TBI's. See what happens....

You're running MAF, just raise you're fuel pressure.... and you should, at the very least, be able to idle and drive on the 305 PROM. Mind you, you won't get the greatest performance with that chip, but it'll run (the MAF somewhat makes up for lack of a prom tune, on stock cars, especially)....

 

hm, ok, i don't know how exactly a knock sensor works so i can't say why the TBI sensor should work here - i will try to get one from a TPI car...

but the O² sensor should be the same - i mean, both systems using a range between 0 and 1 volts


yes i know that - i checked the voltage all over the time the engine was running to make sure the oil pressure switch is ok - also in TunerPro RT theres a value for fuel pump voltage (when reading the 8192 ALDL stream), where it also shows me the 12 volts


i will try this


yes, you're right, but i even don't know for sure that my fuel injectors are all ok (they are the old ones from the donor car), so i thought it would be a good investment to spend some money for new injectors

 

Again, I never swapped from TBI to TPI (so I'm not 100% sure), but from what you're saying though.... you retained the TBI's knock sensor, ESC module, and O2 sensor, and adapted them to the TPI.

I honestly feel that this is where you're problem is. You're throwing no codes because the connectors are all in-tact... but you're ECM might be getting false readings.

 

With a MAF, if you have a 305 prom AND 305 injectors, it should run (steady state) just as well as if it were on a 305, but you won't be able to flow enough fuel at full throttle @ high RPMS. If you were running MAP, though, you'd be way off. I think your problem is hardware, or computer hardware, not calibration settings, yet. Do you have a check engine light wired up? It can tell you if you've burned the chips correctly. You could be running off the limp home stuff which does not perform well.

I thought the oil switch was a BACKUP to the fuel pump relay (and still do think that). It's kind of an anti-stranding device if the fuel pump relay kicks the bucket. It just takes longer to start since it requires the starter to turn the engine enough to build a few psi of pressure. I'm sure it can fail and cause problems like that, but the theory is off, I think.

To test if the knock sensor is causing any problems, just disconnect it. To see if it's working well enough for this test, rev the engine to about 1500 RPMs warm, and tap the block near the knock sensor with a hammer or something, and see if the RPMs drop.

Have you been able to set the timing yet? Did you reconnect the EST bypass after setting it?

BLM and INT at 128 usually means it's still in Open Loop.

Low O2 voltage indicates a lean condition (but doesn't necessarily mean it is). If BLM is HIGH and O2 volts still don't switch (stays below 450 mV), then you're either lean (fuel pressure, injectors, etc...), or have an exhaust leak, or have a bad O2 sensor, or have some injector or ignition problem causing lots of misfire on that bank of the engine. Make sure it isn't in Limp Home mode.

The screen shots that you gave show some contradicting things. in one, the RPMS are 1100 and MAF g/s is 5.77. The other is 675 RPMs and MAF is 10.02 g/s. Both are with closed throttle. But IAC is more open in the lower RPM, which means the engine is struggling quite hard. This would reinforce the "something is starving this thing of fuel" theory, whether it's a bad MAF (or huge vacuum leak), or bad fuel supply (could be injectors). Can you feel each injector click well?
How about the fuel pressure while running? It should be 41 at WOT, and key on engine off, and running with the vacuum reference line disconnected. It should be about 35+ at idle with the vacuum line connected (it may be higher if the engine is running rough = less manifold vacuum). If you want to easily test if it's really lean at idle, just disconnect the vacuum line to the regulator, and see if the engine smooths out (and stick your finger over the line to stop the vacuum leak to the manifold).

Hope this gives you a few more things to try.
Good Luck.

 

thanks for your detailed post!

yes, i can feel every injector is "clicking", but i think it's still a good idea to put in new injectors.

Yes i have a SES light connected - it's off while the engine is running - i also checked the error codes with WinALDL and TunerPro RT >> no codes


i already tried to disconnect it - but the matter with the hammer is a good idea


yep - when the engine was warm it ran ok at about 1000 rpm, then i set the timing to 6° with disconnected bypass, and re-connected it after that


i checked the pressure with key on egine off - i will toy a bit with that matter when i get my new injectors


If you think it could help, i could do a datalog with TunerPro and post it here

but i think you guys are right, and my problem isn't in the calibration but anywhere in the hardware. That's why i now try to start with new injectors.

 

I thought just the opposite. I thought the oil switch was implemented in case the car got into an accident... and rather have fuel cycling with the engine off (key on), the oil pressure switch senses no pressure, shuts down the relay by un-grounding it's internal coil. The ECM then immediately loses it's signal from the relay, causing the ECM to unground the fuel pump.

If memory serves me right (it's been awhile, so please bear with me), won't the engine start with the fuel pump relay disconnected (it just takes a little longer to start, no)? I don't have TPI anymore, so I can't run outside and double check this theory...

 

The fuel pump (FP) oil pressure switch is in parallel with the FP relay contacts. FP relay fails, oil pressure switch keeps the FP running.

RBob.

 

Thanks, RBob.