How long for computer to adjust? (Page 1/1)
Modesto JUN 13, 08:41 PM
So I just rolled over 100 miles on my 3.4 swap. It's still a bit rich at idle and I seem to be able to hear the fuel pump whine at times which was not the case on the stock motor. How long does it take for the computer to adjust after being reset?

Also, any input on tuning? I contacted Ryan at Sinister Performance to get an idea of how that process would work, or locally I have the dyno/afr option. The engine feels great and runs smooth, I just want to be able to pass emissions and make sure I'm not fouling plugs. Thanks!

Edit: The modifications of note are the Crane 272 cam, ported stock exhaust manifolds, 1.52 roller rockers, and Bosch 0280150415 injectors.

[This message has been edited by Modesto (edited 06-13-2020).]

jjd2296 JUN 14, 10:10 AM
My 3.4 swap was running way too rich and fouling plugs. I have a 260h cam with fully ported heads matching lower and middle intake and PPG style plenum with bore tb to 58mm and sprint manifolds and aftermarket y pipe rd performance pulls set up as well. I changed all the plugs double checked everything and got a chip from Ryan. Runs great now. Not rich and is very smooth. Get a chip from Ryan don’t mess around. My next step is to log the data and send it to him for some fine adjustments if needed.
Dennis LaGrua JUN 14, 12:26 PM
If you did the 3.4L swap and used the injectors that came with the engine you will run rich. When the Fiero factory under Ed Parks did those swaps he got around it by using an adjustable fuel pressure regulator but that is really a bandaid fix. The correct way is to adjust the BPC (base pulse constant in the tables of the program) and burn a new chip. If you have the hardware and software its a 5 minute job.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 06-14-2020).]

Modesto JUN 14, 02:43 PM
The injectors are a BMW application that match the needed flow rate with the correct style of injector. From what I understand they are equivalent to just getting the stock 2.8 injectors reflowed only they are suppose to have a better spray pattern.

I pulled a couple of plugs last night and I think they look good?



Does anyone have the cable needed to read and save the data they would be willing to loan or sell?
jjd2296 JUN 14, 06:25 PM
Is your car an 88 r pre 88? I’ve read that those bmw injectors don’t work with the pre 88 ecm.
Modesto JUN 14, 06:59 PM
It's an '88 but I know the ECM was replaced back in 2009. It looks like it shows the part number as being compatible with multiple years though?
Dennis LaGrua JUN 14, 08:55 PM

quote
Originally posted by Modesto:

The injectors are a BMW application that match the needed flow rate with the correct style of injector. From what I understand they are equivalent to just getting the stock 2.8 injectors reflowed only they are suppose to have a better spray pattern.

I pulled a couple of plugs last night and I think they look good?



Does anyone have the cable needed to read and save the data they would be willing to loan or sell?



The Fiero uses a high impedance injector. The Fiero ECM is programmed to control 15 lb injectors. I assume that you are using Bosch injectors?? Look up the part number and find the impedance and the flow rate. I never heard of anyone using injectors designed for a BMW engine on a Fiero. Low impedance (peak and hold) injectors have a resistance of between 2 and 4 ohms. High impedance (saturated) injectors have a resistance of between 10 and 14 ohms Good info here:
Fuel Injector Info
La fiera JUN 14, 09:04 PM
By looking at that spark plug your AFR is about right. BMW injectors are the same resistance as the Fiero, I tell you because I've been using Bosch BMW injectors for a while now.
Joseph Upson JUN 15, 07:53 AM
Having researched early design injectors quite a bit years ago when the info was at the surface of the internet before being buried by modern tech advances, one thing I learned is that the injector coil resistance seems to have little to do with whether it is GM, or BMW, it is determined by the ECM, or engine application. GM used both high and low impedance injectors, with low impedance often being found on some of the boosted applications and HO motors. Simply check the resistance of the injector, which should tell you 2-3 ohms, or ~12 ohms. Low impedance injectors on an ECM designed for high will eventually burn out the injector drivers in the ECM.

You should also acquire the means to check your sensor readings, I don't recall whether the throttle position (TPS) sensor was adjustable, but if it is and it is not positioned correctly it can contribute to this problem. Without a comparison to another motor with the exact same changes, you can't assume that your combo should work okay with the injectors that have worked for others, without further adjustments, especially with an aftermarket cam in place that may also be contributing to the rich condition.

Adjusting fuel pressure within reason should not be an issue, when you consider this is a modified motor and GM already uses some degree of it with the vacuum signal to the regulator to reduce fuel pressure at idle. Perhaps you could cut the perimeter of an old spare regulator diaphragm off and install it as a spacer on top of the current diaphragm to reduce pressure a little. You would need to measure before and after to calculate the change effects if any. On the, Fiero when I needed to raise fuel pressure to increase delivery before programming software was available to me, I simply used coins on top of the diaphragm spring which did the trick.

Just be careful not to create a fire hazard with whatever you do.

[This message has been edited by Joseph Upson (edited 06-15-2020).]

Modesto JUN 15, 06:25 PM
Turns out my buddy has the ALDL cable, he just needs to find it. Sounds like I will probably just log data and send it to Ryan, but I'm suprised the plug looks as good as it does. I might try taking through emissions and see what the numbers say. Maybe it's not as far off as I think?