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DFI and ECMDiscuss all aspects of DFI (Digital Fuel Injection), ECMs (Electronic Control Module), scanners, and diagnostic equipment. Fine tune your Third Gen computer system for top performance.
I am fighting with a 7730 swap in a 86 SC camaro. I was checking the wiring tonight because the flow chart below says that less than .6 volts at the O2 sensor is a bad ecm. All 3 of mine are .37 to .39.
Upon checking the grounds I found a .67 ohm resistance at 20k ohm settings on the ground wire I used for the ECM grounds. Could that have fried my ecms?
That was .67 ohms of resistance within the ground wire that all 4 chassis grounds hooked into.
Is there something else I should be looking at as to why I have a low voltage at the O2 wire connector? Both orange power wires have 12.4 volts coming in.
It's saying that you should be getting between .3 and .6V at terminal GE14. Which means Less than .6V is not a problem unless you're also less than .3V.
You're getting between .37 to .39, so I guess don't see what the problem is.
Also, .67 Ohm resistance on your grounds is actually very good.
The O2 sensor itself doesn't really use any of the ground wires. It grounds through it's body to the exhaust manifold. The O2 sensor ground wire at GE15 is simply a reference ground for the ECM to read the voltage coming in on GE14.
What symptoms/problems are you seeing that's leading you into this diagnostic effort?
Oh ok.
I have a near constant high idle (IAC is new but once it gets to a certain step count say 120 it wont drop below it. IAC passages are complerely clean almost shiney) a very lean running condition (dead cold to headers glowing orange in 15 minutes of driving), the computer sees a nearly constant swing of .1xx to .9xx from the o2 sensor but all the plugs are whitish gray and slightly flakey
A steady 18 inches of vacuum and 43 psi of fuel pressure with key on engine off.
I would think 0.67 ohms is fine. Just to be sure, on my car, I will be running new grounds using #12 stranded THHN housewire from the block, O2 sensor housing, ICM, and ECM chassis to the chassis. You can't have too many.
The engine except for lower intake manifold are all 3.1 from a 91. Charcoal canister, AIR pump and EGR are all removed and disabled in the tune. It was running ok for a while, though the high idke has been an issue since I swapped the block( i swapped the long block, intake, and computer all at different times). I had disabled the AE to try to tune the base table better and it was the second or third day of running no AE with a richer Main BE table to compensate that the engine started running very lean.
My 86 originally had the '302 ecm but I switched it over to the '7730 also out of the 91 Firebird. The BLMs are all over the place. Almost always 128 in open loop, then they jump all over. Form 112 to 135 in the same categories. I can post the last short run when I get back to my laptop.
That's exactly where my frustration is. Aside from the high idle there is no reason I can find why it should be running so lean, yet in approximately 4 miles of city driving the headers were visibly glowing orange and were too hot at the head for my laser heat gun to read. About 7" from the head all 6 cylinders were 980 to 990 degrees
Tell us about your motor. Stock? mods? repairs (timing chain, plugs, etc), last time it ran well?
Your BLMs are a reliable reading of mix. Your engine isn't running lean if your BLMs are good. The BLMs are what the ECM does to the injector pulse width to make the mix stoic. As long as the BLMs don't run out of range (160 on the top end, not sure about bottom), then the mix is stoic since the ECM did not run out of adjustment to reach a stoic reading on the O2.
Form this the most informed posters are convinced that your timing is too retarded. Unburnt mix is finishing combustion in your header. It should be 8 BTDC. Maybe timing chain off or distributor off?
Last edited by Tootie Pang; 09-28-2017 at 11:40 AM.
I had a lean issue when I first put my together years ago.... My issue was the wrong year knock sensors. It did exactly what you are saying and my headers did glow. Did you change those to match your ecm?
250k miles approx. Stock internals besides 1.6 roller tip rockers. New timing chain in May, NGK v power spark plugs 2 weeks old. Stock distributor MSD gold tip cap/rotor serpetine belt accessories. AIR pump delete. EGR delete. 2.8 lower intake and bottom plenum. 3.1 fuel rail-injectors and upper plenum.
Part of the problem is tgat it hasn't run right since the '302 computer died.(12 volt power connected to the 5v signal wire for the fans).
Checked last night and with timing Mark at 0 the rotor is pointed directly at #1 spark plug. Distributor is roughly 45° to the engine block. I don't believe the timing chain is off simply because I spent about 20 minutes checking and rechecking the alignment.
I had a lean issue when I first put my together years ago.... My issue was the wrong year knock sensors. It did exactly what you are saying and my headers did glow. Did you change those to match your ecm?
The knock sensor is still the stock 3.1 sensor. My only concern is that it's the original, but it does read a knock if I tap the block with the key on.
If rule out all other issues before swapping injectors to Bosch-IIIs. That has tuning issues associated it too... it's just be one more variable in the mix (which is never good a thing on diagnostic efforts)
[QUOTE=ULTM8Z;6172221]If rule out all other issues before swapping injectors to Bosch-IIIs. That has tuning issues associated it too... it's just be one more variable in the mix (which is never good a thing on diagnostic efforts)[/QUOTE
Unless you can get the correct offsets and are ready to tune. The link I believe are not Bosch 3s. Contact southbay08.
Ah, understood. Sorry... I got lazy and didn't open the link...
My Miniram came with Gen II's from TPIS and they ran just fine with the stock 7730 $8D voltage offsets. Only reason I changed to Bosch-III's was I needed more capacity.
Physical evidence of running lean but with ECM data saying it's running at stoich would seem to indicate a problem with the O2 sensor (reporting a false rich condition, thereby causing the ECM to pull fuel out unncessarily until the O2 sensor is happy rather than the engine being happy... ).
could be a grounding issue with O2 sensor itself. Try attaching a braided ground strap or a wire to teh O2 sensor body with a hose clamp, and then hooking the other end up to the engine or chassis.
I did that a while back and actually had to retune the VE tables due to the improvement in the grounding scheme (I'm running full length headers, but didn't trust the ground connetction going through a rusty O2 sensor bung, the header tubes, the bolts (with anti-sieze on the threads), etc...
Did we verify his timing is set correctly and ESC functioning correctly? Check out that link over on NastyZ28. Some of their heavy hitters were certain it was timing.
Last edited by Tootie Pang; 09-28-2017 at 04:26 PM.
So E15 was hooked to the cars stock supposedly "O2 ground" at D6 on the '302 connector. The Old D2 wire has some current going to it in open loop key on engine off. Here's the volunteer setting and readout:
D6, D1, D7 were all connected to the D1 ground which had a resistance of .67 between the connector end and the car body with the ohms reader set as below. All 3 are now hooked to a temporary wire with 0 resistance between connector and ground. wh
Also the injectors are black body. I took a picture(see below) of the #1 cylinder injector, but they all look the same. All 6 ohm out between 12.9 and 13.1
Positive is to ecm connector(disconnected from ecm) negative is to known good ground
Ok... how does the blm get locked? Is there something I might have changed that affects that? Both the bin I had when the issue started, and the currect bin are below.
Originally Posted by Tootie Pang
Did we verify his timing is set correctly and ESC functioning correctly? Check out that link over on NastyZ28. Some of their heavy hitters were certain it was timing.
To verify, the when the timing mark is at 0 the rotor should point at the #1 post with the distributor body at a 90* angle to the intake, right?
How do you check if the ESC is working. If its disconnected I get a DTC and I get nothing if its hooked up.
I believe Map kpa was close to 100, maybe I looked at the wrong column.
Um... why would that be??? Other than a few instances where I hammered on it, I never ran wide open. I have the map hooked to a dedicated port, is it supposed to share vacuum?
Your timing should be 8 BTDC with a timing light on the No. 1 cylinder and the EST disabled by pulling the plug by the hood hinge. And yes, No. 1 firing at 0 TDC.
If you unplug the ESC then no spark retard will occur and you may get knock but there will be no knock retard signal to the ECM.
Ok, thank you.
Question, what is the food ohm limit for injectors? The car got to the point tgat it was barely moving, just bogging down. Sounded like trying to take off in 3rd gear. I unplugged the #1 injector because the #1 spark plug was nearly black. After I was able to drive it home almost running like it should. It was still rich but not nearly as bad. I'm going to check all the other injectors again tomorrow.
Ok. Ya my expectation is that I'll find one that's higher tgat the rest. Right now it's #1 with a 13.5 to the 12.9 of all the other injectors previously
That is my hope too although I'm worried about the fact that the headers were still glowing orange even with that injector unhooked.
I'm going to go get a set of 2.9l ford injectors from the junkyard.
Also the wire that I had hooked up as the O2 ground had a reading of 013 volts on the 200mv setting key on engine off.Could this have hurt the O2 sensor or is it most likely ok?
That is my hope too although I'm worried about the fact that the headers were still glowing orange even with that injector unhooked.
I'm going to go get a set of 2.9l ford injectors from the junkyard.
Also the wire that I had hooked up as the O2 ground had a reading of 013 volts on the 200mv setting key on engine off.Could this have hurt the O2 sensor or is it most likely ok?
Just curious why would you use old dirty junk yard injectors. Bye the time you have them serviced your at the price of southbays.
So I have a set of 02 injectors lying around. Can I use those in place of the stock ones with just a injectors flow display change and a change to the VE tables?
Just curious why would you use old dirty junk yard injectors. Bye the time you have them serviced your at the price of southbays.
My only reason for considering used injectors is to get it running good. Once I've got it fixed I've got a 2002 3100 top end waiting, with a 3800 blower and custom lower intake in the wings. I have a hard time justifying new injectors for 3 months(maybe) just to buy new injectors again in spring.
09-27-2017, 09:28 PM
