ATTN: Injection/ECU/LM Gurus!!

[BIGBRUDDA]

Earlier this summer I performed the "87 T2" conversion on my 86 Daytona C/S. It drove fine to SDAC-18 on the 86 electronics/G valve+sensor bleed. There I finished the electronic conversion, under the guidance of several well known assistants and went with an 87(#171)type Logic Module.
Since then the car has acted erraticly, to say the least!
At 7 lbs of Boost it goes way rich. Black cloud- coughing- sputtering -lawnmower rich.The condition manifests itself at any speed, any throttle setting. Just in excess of 7PSI!
I have changed 2 different MAP sensors, 3 different TPS sensors,(all tested good),converted to a brand new 4wire O2 sensor, and 2 other LM units( one 87 t1 auto, one 87 custom cal). Changed to 29 lb/hr injectors from 32. And a different injector harness.I changed from Champion RN9yc plugs to NGK/GR5. I've verified the wiring 3 different times using DATA/schematics provided by Dodgegarage and Russ Knize No difference!
I monitor the O2 sensor with a digital VOM.The meter reaches 600 to 630mv at 7PSI,then goes spastic and shows - thats negative voltage! I've used Reeves scanner on 2 occasions and its showed no error codes. And only a rich condition, and timing retard on DATA logs.The engine runs fine below 7PSI although a little rich.
Sooooooo................. WHAT DA HELL IS WRONG!!??

[badandy]

Earlier this summer I performed the "87 T2" conversion on my 86 Daytona C/S. It drove fine to SDAC-18 on the 86 electronics/G valve+sensor bleed. There I finished the electronic conversion, under the guidance of several well known assistants and went with an 87(#171)type Logic Module.
Since then the car has acted erraticly, to say the least!
At 7 lbs of Boost it goes way rich. Black cloud- coughing- sputtering -lawnmower rich.The condition manifests itself at any speed, any throttle setting. Just in excess of 7PSI!
I have changed 2 different MAP sensors, 3 different TPS sensors,(all tested good),converted to a brand new 4wire O2 sensor, and 2 other LM units( one 87 t1 auto, one 87 custom cal). Changed to 29 lb/hr injectors from 32. And a different injector harness.I changed from Champion RN9yc plugs to NGK/GR5. I've verified the wiring 3 different times using DATA/schematics provided by Dodgegarage and Russ Knize No difference!
I monitor the O2 sensor with a digital VOM.The meter reaches 600 to 630mv at 7PSI,then goes spastic and shows - thats negative voltage! I've used Reeves scanner on 2 occasions and its showed no error codes. And only a rich condition, and timing retard on DATA logs.The engine runs fine below 7PSI although a little rich.
Sooooooo................. WHAT DA HELL IS WRONG!!??

Exactly how much timing retard at 7 psi? I'm curious if you might have an over zealous knock sensor?

[BIGBRUDDA]

Exactly how much timing retard at 7 psi? I'm curious if you might have an over zealous knock sensor?

We'll hafta ask Warren. He downloaded it. Then gave me a"synopsis".

[ShelGame]

Have you checked the FPR for leaks/function?

I don't really think that's it. But, it's a good thing to check.

Here's what I think is going on - A negative O2 voltage will be read by the LM as 0V (It can't read a negative voltage). Which indiates a lean condition. It then goes to full enrichment trying to correct the 'lean' condition.

So, you have to figure out what causes the O2 to generate a negative voltage.

Have you triple checked the 4-wire O2 wiring? I dunno why it would coincide with 7psi either. There really shouldn't be any correlation betwen them. Maybe it's just a coincidence?

[mario03SRT]

Earlier this summer I performed the "87 T2" conversion on my 86 Daytona C/S. It drove fine to SDAC-18 on the 86 electronics/G valve+sensor bleed. There I finished the electronic conversion, under the guidance of several well known assistants and went with an 87(#171)type Logic Module.
Since then the car has acted erraticly, to say the least!
At 7 lbs of Boost it goes way rich. Black cloud- coughing- sputtering -lawnmower rich.The condition manifests itself at any speed, any throttle setting. Just in excess of 7PSI!
I have changed 2 different MAP sensors, 3 different TPS sensors,(all tested good),converted to a brand new 4wire O2 sensor, and 2 other LM units( one 87 t1 auto, one 87 custom cal). Changed to 29 lb/hr injectors from 32. And a different injector harness.I changed from Champion RN9yc plugs to NGK/GR5. I've verified the wiring 3 different times using DATA/schematics provided by Dodgegarage and Russ Knize No difference!
I monitor the O2 sensor with a digital VOM.The meter reaches 600 to 630mv at 7PSI,then goes spastic and shows - thats negative voltage! I've used Reeves scanner on 2 occasions and its showed no error codes. And only a rich condition, and timing retard on DATA logs.The engine runs fine below 7PSI although a little rich.
Sooooooo................. WHAT DA HELL IS WRONG!!??

Big,

Couple of questions.

What did/do you change elec/mechanically when you did the T2 upgrade? Turbo? Injectors? Map? I/C?

The voltage readings that you mention were they at WOT? Or part throttle?

If WOT you are Wayyyy to lean. Of course this would splain the "-" meter reading. The time I spent in narrowbandville back in the late 90's tells me that you need to be in the .9v range to be safe @ WOT. But as we all know this is a vague/ambiguous reading of true AFR which is especially important on a forced induction motor. Recently when my car went to the dyno and we did WB vs 02 from an OTC there were significant differences in 02v and the WB readings. Don't tune your car to that stuff. Borrow a WB, sorry mines hard wired in.


A sensor output 6v is in the range of a sensor "stoiching" not at WOT, FYI. But its quite possible especially with the super spooling Mitsu to see 7 psi at part throttle all day as you accelerate moderately.

Could you pump be taking a poop?

FYI,
Marion

[BIGBRUDDA]

Ok Guyz : The "Autozone"fuelpump delivers 55psi at idle. I've disconnected the vac line, to see if constant rate helped, and once again .....NO difference.
Yes, the 4 wire O2 has been checked 3 times. As per both ,Tony Hanna posts and Dodgegarage instructions.
Voltage reading are via a digital VOM @ the LM terminal. WOT generates almost immediate 600mv signal , then Mayhem!! Partial throttle will generate 600+mv signal prior to Mayhem! The 600mvsignal and 7PSI do co-incide.
The setup is stock Garrett turbo,W/latemodel compressor housing. 89 T2 1 piece manifold. Both, stock T2 I/C, and without.
On the way to SDAC the car ran OK on the 86 LM& sensors. A little knock at 4500 RPM. Didn't take over 5000 RPM.

And although the negative O2 readings indicate a lean condition. The black smoke and petro smell say not.
I too am curious about the knock sensor, and the charge temp sensor. Since all others are "apparently" within 1989 standards.
Sorry but I am constrained by "shade tree& hand tool" capabilities.

[mario03SRT]

Ok Guyz : The "Autozone"fuelpump delivers 55psi at idle. I've disconnected the vac line, to see if constant rate helped, and once again .....NO difference.
Yes, the 4 wire O2 has been checked 3 times. As per both ,Tony Hanna posts and Dodgegarage instructions.
Voltage reading are via a digital VOM @ the LM terminal. WOT generates almost immediate 600mv signal , then Mayhem!! Partial throttle will generate 600+mv signal prior to Mayhem! The 600mvsignal and 7PSI do co-incide.
The setup is stock Garrett turbo,W/latemodel compressor housing. 89 T2 1 piece manifold. Both, stock T2 I/C, and without.
On the way to SDAC the car ran OK on the 86 LM& sensors. A little knock at 4500 RPM. Didn't take over 5000 RPM.

And although the negative O2 readings indicate a lean condition. The black smoke and petro smell say not.
I too am curious about the knock sensor, and the charge temp sensor. Since all others are "apparently" within 1989 standards.
Sorry but I am constrained by "shade tree& hand tool" capabilities.

Bad boost signal to regulator defeating the 1 to 1?

Does the voltage ever exceed .6v? Is that the ceiling? With all that supposed fuel you should be reading 02 voltage like a full 1.1 or 1.2v's, meaning your douching the engine, on the 0-1v scale.

Marion

[BIGBRUDDA]

NOPE! never seen over 630 mv. I'm curious about "shorting" the O2 signal. Is that possible?

[mock_glh]

This may seem unrelated but I was once given a job to cure a similar condition in a GLHS. Reducing the fuel pressure improved the condition but power was still down. After checking and changing all of the electronic components (including the wireloom) without success, I suspected something mechanical. I pulled the cam sprocket and found the keyways to be badly beaten out. I installed another cam and sprocket and all was good. It's easy enough to check, give it a try.

[TopDollar69]

Are you saying you had the same fuel pressure with the regulator hooked up to vacuum at idle as you do with it unhooked?

[mario03SRT]

NOPE! never seen over 630 mv. I'm curious about "shorting" the O2 signal. Is that possible?

Timbo,

I always tapped into the sig out wire from the sensor to get my readings. Which is the black lead on the 4 wire 02 harness AFAIK.

Marion

[mario03SRT]

Are you saying you had the same fuel pressure with the regulator hooked up to vacuum at idle as you do with it unhooked?

I believe that he is saying theat there was no signal output change.

[black86glhs]

You do have all the grounds hooked up, correct? Could be a faulty O2. You 100% sure the LM pins are in the right spot?
My GLHS acted weird in all sorts of ways until I got the vaccum hoses straightened out and the LM wiring corrected. The harness I used was for a T-II car so the pins were off on a few of them.

[sdac guy]

If it is a stock T2 cal/LM, then you should have the O2 switching lean/rich at idle when hot (closed loop). That reading should be about .9v. .6v is way to low at any time. So there is a problem in the O2 circuit. Make sure the braided ground from the fuel rail to the firewall makes a good connection. Make sure the braided ground that jumps the right side engine mount makes good connection. Make sure your signal ground from the O2 sensor makes a good connection (some folks run it back to the battery neg terminal).

Try measuring the O2 from it's 4 wire connector to see if it is a better reading. If it is, then the wiring between the sensor and the LM is suspect.

Barry

[IROCNOROLL]

OK Guyz : The "Autozone"fuel pump delivers 55psi at idle. I've disconnected the vac line, to see if constant rate helped, and once again .....NO difference.

55PSI at IDLE vacuum line connected? What about pressure at idle when the vacuum line is disconnected? 8+ psi increase?

Yes, the 4 wire O2 has been checked 3 times. As per both ,Tony Hanna posts and Dodgegarage instructions. Voltage reading are via a digital VOM @ the LM terminal. WOT generates almost immediate 600mv signal , then Mayhem!! Partial throttle will generate 600+mv signal prior to Mayhem! The 600mvsignal and 7PSI do co-incide.

600mv is just off Stoich. This is too lean for part to full throttle on an N/A engine, little less one with artificial aspiration. And you say the readings are steady there? Even at idle the 02 voltage should be bouncing or crossing say from 100mv to 800+mv several times per second once things are warmed up and closed loop has latched. At WOT, the 02 is ignored by the LM, and should not have any affect on the condition one way or the other.Try to take the readings at the 02 cell itself, and test using the sensor ground vs the battery ground to see if there is a different read. There may be a ground issue at the LM connector end of the harness, and changing all the pieces you have tried will not make a difference if there is a poor connection / harness issue. Verify all the grounds for the LM and the PM are correct and clean voltage drop wise.

There is also the problem called negative bias 02 cell. This would describe what you are seeing with the DVOM. This is usually caused by an internal short in the 02 sensor tip inside the shield. And replacing the cell usually corrects this. But you've been there, with this one already. Another way to cause a negative bias 02 reading, aside from harness resistance / mis-pinned / short issues, is to contaminate or block the fresh air supply to the atmospheric vented side of the 02. But the 02 cell has been changed to no change to the condition, yes?

We have also seen a couple of instances where there has been excessive valve guide / seal wear on the exhaust valves that allowed a large crankcase vent supplied 02 leak along with engine oil directly into the exhaust manifold. Smoke and a very lean read from the 02. True, oily blue, not the black your experiencing, but a contributing factor none the less. Aftermarket cams, especially regrinds, with mis-aligned rocker tip contact to the valve stems cause extra side loading on the valve stems, and eat the guides prematurely. FWTW.

Also, as there seems to be a corrolation between 7PSI, and the fueling issue, is there any possibility of a Wastegate issue. 7-8psi is the point the WG will usually push open if the WG control circuit is connected directly to a manifold vacuum source or the WG solenoid control hose is plugged / cycled closed by the LM, the wg solenoid vent is plugged, or the wg solenoid is stuck closed. If there is, say, a large air leak associated with this WG opening, the 02 would be the next device in the direct path of this false air flow. Just thinking out loud here.

The setup is stock Garrett turbo,W/late model compressor housing. 89 T2 1 piece manifold. Both, stock T2 I/C, and without.
On the way to SDAC the car ran OK on the 86 LM& sensors. A little knock at 4500 RPM. Didn't take over 5000 RPM.

Does this housing incorporate an EGR valve? If it does, is it still there?

And although the negative O2 readings indicate a lean condition. The black smoke and petrol smell say not.

The black smoke is a "result" of the low to negative 02 sensor voltage input to the LM. As long as the LM believes it is seeing these minimal "low" MV readings from the 02, it will continue to run long injector pulse times, to the point of stalling the injectors open. This will for sure make the black smoke you have. Also, if the meter you are using is not a high impedance 10 megohm per volt device, the meter itself may cause the negative voltage readings on the very low current capable 02 output circuit.

An issue on the MAP harness will potentially give you the same condition by altering the actual voltage output "read" at the LM. This may also give the condition to create the pig rich deal. This may also explain the 7psi boost correlation? Not enough issue to set a code, but enough to really upset the calibration.

I too am curious about the knock sensor, and the charge temp sensor. Since all others are "apparently" within 1989 standards.
Sorry but I am constrained by "shade tree& hand tool" capabilities.

Check the resistance of the CTS and the CAT sensors after a 12+ hour cold soak. They should be close, indicating that they are in the same calibration. Temp sensors would have the potential to create the rich condition long before the knock input. Knock sensor calibration would at best cause a timing retard back to base, which in itself should not create the issue you are experiencing.

Anyways... it's getting too late to keep going here, but you get the idea I hope?

[BIGBRUDDA]

Are you saying you had the same fuel pressure with the regulator hooked up to vacuum at idle as you do with it unhooked?

No. The thought was to defeat the "rising rate" feature,IE feed a constant pressure to the fuel rail.( and eliminate the possibility of a faulty REG) The reading (55PSI) was taken off the rail at idle, no vacuum signal. And,showed no difference in rich condition.

[Clay]

No. The thought was to defeat the "rising rate" feature,IE feed a constant pressure to the fuel rail.( and eliminate the possibility of a faulty REG) The reading (55PSI) was taken off the rail at idle, no vacuum signal. And,showed no difference in rich condition.

but the LM can defeat that by increasing pulse width. Sounds more and more like an issue somewhere with the O2 sensor/circuit being lean, when in fact its actually very rich.

[BIGBRUDDA]

Is there a chance the injector driver circuit could be malfunctioning?A mismatch between the LM and power module?A transistor misfiring? LM sees WOT and 7PSI sends signal to flakey triac?

[BIGBRUDDA]

And yes the O2 signal "toggles" normally at sub 7PSI conditions. 90-108mv @idle , and up to400+mv puttin down the street.

[Clay]

i dont know, the fact that you see 0.6 volts when the thing is pig rich points to the O2 sensor/circuit.