Need ECM guidance
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Car: 1991 GTA T-Top / 2014 Mustang GT
Engine: 5L TPI
Transmission: WCT5
Axle/Gears: 3.42
Need ECM guidance
My car has a stalling problem that's been driving me nuts for far too long now. Turn the car on after it's been sitting and it runs perfectly. No backfires, full power, flawless idle, and it will stay like that sometimes for hours. Then randomly the engine light will come on, the car will lose all power and start bucking and backfiring, then eventually stall. Only code showing is a code 44 which means it's running lean. There is no build up to the stalling though, it just randomly happens. Sometimes I'll stop for gas, or stop at a store where I only turn the car off for a minute, and when I start it again it runs like trash. Or I'll drive it for 8 hours and never have a hint of an issue.
The car has high km, and last summer I had a full tune up done, all sensors changed, as well as all intake gaskets. I'm 99.9% sure there are no vacuum leaks and as I said, it runs perfectly until it goes to s***. All of this started immediately after I did all of that work so l'm thinking that from a combination of age, sitting for a few years, and the big tune up, maybe the ECM is calling it quits. Now I need some guidance in regards to ordering a new ECM as I'm not very familiar with them. My car's a 91 LB9 GTA with a 5 speed and no modifications. Do I just order any LB9 ECM and keep the chip from my current one and swap it in to the new one? Or do I need to order the full shebang? Rookie questions I know, but I want to confirm before wasting money on the wrong part. Also, what's the best place to order from? Hawks seems to only have a used one.
The car has high km, and last summer I had a full tune up done, all sensors changed, as well as all intake gaskets. I'm 99.9% sure there are no vacuum leaks and as I said, it runs perfectly until it goes to s***. All of this started immediately after I did all of that work so l'm thinking that from a combination of age, sitting for a few years, and the big tune up, maybe the ECM is calling it quits. Now I need some guidance in regards to ordering a new ECM as I'm not very familiar with them. My car's a 91 LB9 GTA with a 5 speed and no modifications. Do I just order any LB9 ECM and keep the chip from my current one and swap it in to the new one? Or do I need to order the full shebang? Rookie questions I know, but I want to confirm before wasting money on the wrong part. Also, what's the best place to order from? Hawks seems to only have a used one.
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Re: Need ECM guidance
Fuel pump could be going out, or the fuel filter is clogging.
As for an ECM, order the proper one (1227730) and swap the MEMCAL and small cover over to it.
RBob.
As for an ECM, order the proper one (1227730) and swap the MEMCAL and small cover over to it.
RBob.
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Car: 1991 GTA T-Top / 2014 Mustang GT
Engine: 5L TPI
Transmission: WCT5
Axle/Gears: 3.42
Re: Need ECM guidance
Both were replaced fairly recently, and if the pump were going, wouldn't it be more consistent? I drove the car one day for hours without a single sign of anything, then turned it off for maybe 2 minutes at a store, then when I started it again it instantly ran like trash. Had to let it sit for a few hours then it started back up and drove perfectly again. Also where would you suggest ordering from? I don't really want a cheap junk one, nor do I want a used one
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Car: 1988 iroc-z (original owner)
Engine: 305
Transmission: 5-speed manual
Re: Need ECM guidance
Back in the summer of 2000 mine would inconsistently sputter and loose power. In the spring of 2001, before bringing it out of storage, I replaced the fuel filter and thought that the problem was fixed; however, it began to sputter occasionally a few weeks later. In spite of no codes being thrown (!), I checked vacuum lines, hoses, plenum for leaks around gaskets: anything and everything. I'll never forget the day that I replaced the fuel pump. (My wife was due with our second and he was born just after midnight: Sep 12, 2001.) I couldn't make it up the hill right by our house, so I limped it back into the garage and listened watched the news all day.
It was the fuel pump. It was inconsistent.
It was the fuel pump. It was inconsistent.
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Car: 1991 GTA T-Top / 2014 Mustang GT
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Re: Need ECM guidance
Is there a way to test it without dropping the tank? It's a Delco and it isn't even 2 years old, it's also odd that it would start doing this nonsense directly after I did a bunch of work as I don't see how anything could have been a trigger
#6
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Re: Need ECM guidance
ECM's can fail. It happens. I had a MAF ECM (7165) die on my car. You could tap in it and the engine ran differently - sometimes wouldn't even run. Smack it again and back to normal. Cracked circuit board I assume. Swapped it out and problem resolved.
You could install a wideband so you can see the actual AFR's. They are relatively cheap these days. I just put in the AEM x-series for my EBL tuning and it was less than $150.
Have the injectors been replaced? Sounds like they might be heat soaking when you stop the engine and possibly having coil failure. Check the resistance on them cold and hot. It shouldn't change. If it does they are shorting out when hot.
GD
You could install a wideband so you can see the actual AFR's. They are relatively cheap these days. I just put in the AEM x-series for my EBL tuning and it was less than $150.
Have the injectors been replaced? Sounds like they might be heat soaking when you stop the engine and possibly having coil failure. Check the resistance on them cold and hot. It shouldn't change. If it does they are shorting out when hot.
GD
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Car: 1991 GTA T-Top / 2014 Mustang GT
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Re: Need ECM guidance
I checked them the last time that I had an issue and they all seemed perfect. They were all replaced last summer from Southbay so I was hoping they weren't toast already haha. As for the ECM, I figured I'd replace it anyways because if it hasn't given up yet, at it's age it's only a matter of time. Where did you get you replacement from?
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Re: Need ECM guidance
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Re: Need ECM guidance
It’s a plug and play just disconnect your battery.The ecm is in a bracket that drops down on your passengers side under the dash below your dash speaker. 2 screws hold it to the dash frame. The 3 connectors at the ecm. Push down and hold the tab on the connector wiggle the connector while pulling it. NSwap over your memcal it gets released bye rocking back the blue and white levers. Reinstall your access cover and your good to go. The 1227730 is for 90-92 tpi speed density and 90-92 3.1l.
#11
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Re: Need ECM guidance
Ah yes if you have new injectors from SouthBay then I would doubt that is your problem. It is starting to sound a lot like the ECU may be at fault. You would really have to catch it acting badly and then try to hookup a scope to various inputs and outputs to see if you could narrow it down but being intermittent, and being the ECM is fairly inexpensive - I would just swap it and see what happens. Or go to something like the EBL system from RBob's DynamicEFI (that's what I'm running and it's excellent):
https://www.dynamicefi.com/
GD
https://www.dynamicefi.com/
GD
#12
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Car: 1991 GTA T-Top / 2014 Mustang GT
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Re: Need ECM guidance
Are you using that on a stock motor?? More out of curiosity. It would be a nice upgrade but probably something I'll leave for down the road a bit
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Re: Need ECM guidance
Also with SouthBay Bosch III's you will benefit from tuning even on a stock engine. With EBL this is very simple.
GD
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Car: 1991 Z28
Engine: 305 TPI
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Re: Need ECM guidance
You can test your fuel pump by taping the FPG gauge to the windshield, facing in the car and drive around the block. If you could do this while it is acting up it will help eliminate this from the equation.The pressure should be At 33psi @ idle and 43 at WOT give or take a couple pounds.
You said you did a full tune up. Did this include the ICM in the bottom of the dizzy? I only say this because I had a similar problem with similar issues, backfire, sputter and die, the inconsistency to be the big one. It ended up being the ICM. It took me a few weeks and a whole thread to finally find the culprit, I was sure it was fuel related and that turned out to not be the case..
You said you did a full tune up. Did this include the ICM in the bottom of the dizzy? I only say this because I had a similar problem with similar issues, backfire, sputter and die, the inconsistency to be the big one. It ended up being the ICM. It took me a few weeks and a whole thread to finally find the culprit, I was sure it was fuel related and that turned out to not be the case..
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Car: 1991 GTA T-Top / 2014 Mustang GT
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Re: Need ECM guidance
You can test your fuel pump by taping the FPG gauge to the windshield, facing in the car and drive around the block. If you could do this while it is acting up it will help eliminate this from the equation.The pressure should be At 33psi @ idle and 43 at WOT give or take a couple pounds.
You said you did a full tune up. Did this include the ICM in the bottom of the dizzy? I only say this because I had a similar problem with similar issues, backfire, sputter and die, the inconsistency to be the big one. It ended up being the ICM. It took me a few weeks and a whole thread to finally find the culprit, I was sure it was fuel related and that turned out to not be the case..
You said you did a full tune up. Did this include the ICM in the bottom of the dizzy? I only say this because I had a similar problem with similar issues, backfire, sputter and die, the inconsistency to be the big one. It ended up being the ICM. It took me a few weeks and a whole thread to finally find the culprit, I was sure it was fuel related and that turned out to not be the case..
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Re: Need ECM guidance
Code 44-This code will be set whenever the ecm perceives a lean exhaust condition. The main causes for this is a grounded O2 sensor, low fuel pressure, restricted injectors, contaminated fuel, exhaust leaks or bad air switching valve. The condition met to set the code is a low O2output voltage (less than 0.2V)around a minute with the ecm is closed loop.
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Re: Need ECM guidance
Code 44-This code will be set whenever the ecm perceives a lean exhaust condition. The main causes for this is a grounded O2 sensor, low fuel pressure, restricted injectors, contaminated fuel, exhaust leaks or bad air switching valve. The condition met to set the code is a low O2output voltage (less than 0.2V)around a minute with the ecm is closed loop.
from chevythunder.com
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Re: Need ECM guidance
Injectors are new and have been tested to not be the issue when the car acts up, I can't check until spring but I doubt it's the issue, not bad gas. I do have an exhaust leak at the bottom of the manifold (not where it meets the block) but I've had it for a long time and never had this issue so I can't imagine it's the culprit. Once that code has been triggered, will it ever reset on its own? I can start the car and pull that code even when it's running totally perfectly. The check engine light only comes on when the car starts to get sketchy
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Re: Need ECM guidance
I had a somewhat different situation that turned out to be the ECM in my ‘89 TPI IROC which began to run very rich, surging, zero power, blowing smoke, stalling, fouling plugs and basically running like crap. The code I pulled was #45-o2 sensor RICH exhaust. The shop started out by checking fuel pressure which was good, injector leak down test was good, maf sensor good, o2 sensor good, injector ohm test good. (BTW the cts sensor was replaced due to corrosion by a different shop and also took apart the tank pressure valve and cleaned it) The shop also replaced the ignition module, but it didn’t remedy my problem. The shop manager called me one day and said he believed he had narrowed it down to the ECM and ordered an ECM for delivery. The replacement ECM turned out to be bad, so he ordered a second unit, installed it and problem solved. Apparently my faulty ECM was misreading a lean condition and responding by having the injectors pump more gas. A bad ECM can often lead you on a wild goose chase. HTH
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Car: 1991 GTA T-Top / 2014 Mustang GT
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Re: Need ECM guidance
I had a somewhat different situation that turned out to be the ECM in my ‘89 TPI IROC which began to run very rich, surging, zero power, blowing smoke, stalling, fouling plugs and basically running like crap. The code I pulled was #45-o2 sensor RICH exhaust. The shop started out by checking fuel pressure which was good, injector leak down test was good, maf sensor good, o2 sensor good, injector ohm test good. (BTW the cts sensor was replaced due to corrosion by a different shop and also took apart the tank pressure valve and cleaned it) The shop also replaced the ignition module, but it didn’t remedy my problem. The shop manager called me one day and said he believed he had narrowed it down to the ECM and ordered an ECM for delivery. The replacement ECM turned out to be bad, so he ordered a second unit, installed it and problem solved. Apparently my faulty ECM was misreading a lean condition and responding by having the injectors pump more gas. A bad ECM can often lead you on a wild goose chase. HTH
That's exactly what brought me to originally assume ECM. Your situation sounds like it's exactly mine but rich instead of lean, though I imagine it can go either way. I'm excited to get the new ECM in and see how the car runs. In the few years I've owned it, it's given me so many issues that I have yet to drive it at it's peak potential. I really hope this gets me there haha
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Re: Need ECM guidance
I wasn't familiar with that but it seems that if it's showing wrong readings, it still points back to likely the 02 Sensor or the ECM no?
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Re: Need ECM guidance
GD
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Re: Need ECM guidance
I want to tackle this so badly but unfortunately I'm still limited to what I can do in the garage until spring. I've never had the car act up without hours of driving so I doubt a reader would pick up anything conclusive with just a few minutes of idling
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Re: Need ECM guidance
No - you need to have a reader with you at all times so you can whip it out when the trouble begins. But it would be useful to know where the BLM's are now with the Bosch III's. They tend to throw off the calibration quite a bit so it's probably already adding tons of fuel and I bet the BLM's are high. Many people report that without tuning for injector size and especially for injector latency and short pulse width values the Bosch III's run lean with BLM's up around 160 so the ECM is adding fuel all the time. It may be borderline till something else pushes it over the edge. You really need a custom chip or an actual tuning solution like the EBL if you are going to run them properly. People get away with it, but it's absolutely not correct to just throw them in and turn the key.
GD
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Re: Need ECM guidance
I ordered the 19lb ones though, not the 24 as I wanted to avoid having to do any tuning. Do I need to get a tune even with the 19's?
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Re: Need ECM guidance
If you have a 305 you need to get 19#hr injectors or tune for 24s.
Even with the 19s you need to set the battery voltage offsets or you will run lean.
Or you can use these injectors they should be a direct replacement. Although tuning will help if it’s lean it’s not the cure for your problem.
https://www.southbayfuelinjectors.co...-1986-1992-851
https://www.thirdgen.org/forums/diy-...0-voltage.html
Last edited by Tuned Performance; 02-06-2019 at 04:24 PM.
#32
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Re: Need ECM guidance
Right - unfortunately it has been found through a lot of board member experience (including my own) that the 19's will run without tuning, though they act like a 17.5 lb injector, and the offsets are wrong.... like I said they run and the ECM doesn't generally complain, but it's far from optimal. South Bay is good people, but they are not tuners, and though the injectors do flow 19lb on a bench, due to the 1980's programming they don't *run* like the original 19's did. So for purposes of the TPI system you must set it to 17.5 for correct BLM's. Similarly, the 24's (which I currently have) run like a 22.5 injector.
The 19 Bosch III's are good injectors and run really well when properly tuned. But, like all injectors that are not EXACTLY like the originals, there is a LOT more to an injector than it's size - injector voltage offsets, short PW corrections, upper and lower non-linear flow areas.... to name just a few. And all that must be taken into account by the software. If it's not, the results will not be like stock operation.
GD
The 19 Bosch III's are good injectors and run really well when properly tuned. But, like all injectors that are not EXACTLY like the originals, there is a LOT more to an injector than it's size - injector voltage offsets, short PW corrections, upper and lower non-linear flow areas.... to name just a few. And all that must be taken into account by the software. If it's not, the results will not be like stock operation.
GD
#33
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Car: 1991 GTA T-Top / 2014 Mustang GT
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Axle/Gears: 3.42
Re: Need ECM guidance
If you have a 305 you need to get 19#hr injectors or tune for 24s.
Even with the 19s you need to set the battery voltage offsets or you will run lean.
Or you can use these injectors they should be a direct replacement. Although tuning will help if it’s lean it’s not the cure for your problem.
https://www.southbayfuelinjectors.co...-1986-1992-851
https://www.thirdgen.org/forums/diy-...0-voltage.html
Right - unfortunately it has been found through a lot of board member experience (including my own) that the 19's will run without tuning, though they act like a 17.5 lb injector, and the offsets are wrong.... like I said they run and the ECM doesn't generally complain, but it's far from optimal. South Bay is good people, but they are not tuners, and though the injectors do flow 19lb on a bench, due to the 1980's programming they don't *run* like the original 19's did. So for purposes of the TPI system you must set it to 17.5 for correct BLM's. Similarly, the 24's (which I currently have) run like a 22.5 injector.
The 19 Bosch III's are good injectors and run really well when properly tuned. But, like all injectors that are not EXACTLY like the originals, there is a LOT more to an injector than it's size - injector voltage offsets, short PW corrections, upper and lower non-linear flow areas.... to name just a few. And all that must be taken into account by the software. If it's not, the results will not be like stock operation.
GD
The 19 Bosch III's are good injectors and run really well when properly tuned. But, like all injectors that are not EXACTLY like the originals, there is a LOT more to an injector than it's size - injector voltage offsets, short PW corrections, upper and lower non-linear flow areas.... to name just a few. And all that must be taken into account by the software. If it's not, the results will not be like stock operation.
GD
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