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Charlie don't surf..
'92 Ford Bronco XLT
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14,965 Posts
Discussion Starter #1
Up until now, my engine has been running great ever since installing the Tweecer. Went camping this weekend, 40 miles each way. No problem going down, but when I got in this morning to leave and turned onto the highway, I noticed it was shifting strange, almost like it was lugging in 1st gear. The CEL came on and went off, I didn't have any problems once I was up to speed, but if I came to a stop and then started again I could feel something was not right..started thinking it was the tranny until I got home and pulled these codes with my Scantool

511 PCM ROM Failure..this is not good, but I'm thinking it might have something to do with one of the tunes I loaded to the Tweecer.

122 TP or Accel pedal position signal too low
211 Profile Ignition Pickup Erratic

I'm guessing the fact that these three codes popped at the same time when it had been running great isn't coincidence. Wondering if the 511 code is the root cause of the other issues.

I was thinking I'd try reloading my base tune and see what happens, any other suggestions?
 

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511 is just because the computer is reading and using the Tweecer ROM and not the EECs. It's normal with a tuner or chip. It won't throw a check engine light.

122 check the TP sensor voltage return. They do go bad and can be adjusted.

211 damn, is that dizzy going? I think there are some ignition tests in the Haynes manual. It is best to replace the TFI and Ignition pick-up together. I have replaced a few dizzies and/or replaced the pick-up and tfi

I have also had hiccups that went away with a reset of the computer.
 

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Charlie don't surf..
'92 Ford Bronco XLT
Joined
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14,965 Posts
Discussion Starter #3
Been running the Tweecer for several months and have never seen the 511 code before, so why would it pop now??

I'd be pissed if the TPS is bad, the thing is brand new, same with the TFI. It's maybe 4 months old and it's a Motorcraft...Not sure about the dizzy. Can't imagine it's bad but I guess those pick up can take a crap...If not one thing it's another with this rig..

511 is just because the computer is reading and using the Tweecer ROM and not the EECs. It's normal with a tuner or chip. It won't throw a check engine light.

122 check the TP sensor voltage return. They do go bad and can be adjusted.

211 damn, is that dizzy going? I think there are some ignition tests in the Haynes manual. It is best to replace the TFI and Ignition pick-up together.
 

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Reset the computer then and see if they reappear.

I did not get the 511 code immediately, it's there now.

It wouldn't hurt to reload the tune, but I would wait to see if resetting the eec will work.


I chased tfi/dizzy troubles for months once, found out the 22k Ohm resister between the dizzy and eec was bad. I am not saying that is what's with yours just empathizing, sucks sometimes. I found it and fixed it then got a new harness anyway. These rigs are getting old.

I was able to set the scaler checksum base address to zero to eliminate the ROM read failure with the Mustang computer. I don't see that scaler in the AHACA nor VEX1 strat.
 

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Charlie don't surf..
'92 Ford Bronco XLT
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14,965 Posts
Discussion Starter #5
Reset the EEC last night and reloaded my base calibration.. Got this from MG @ Tweecer. Pretty much exactly what you said, except he updated the strategy. Thought it would be good info for you too..

"511 is due to the change in the calibration. set the checksum base
address to zero to clear that one. The others are the cause for the
shifting, PIP is used throughout the strategy for different things
including trans functions. TFI, distributor, etc....

You can check the TP signal with the key on, engine off and RT logging.
Sweep the throttle slowly to the floor and back watching/logging the tps
voltage and see if you get drop outs/spikes in the voltage."

Also, MG updated the VEX1 and AHCA strategies to fix the problem..

"I located the checksum base address for VEX1 and AHACA, they have both
been uploaded to the Software Updates folder in the files section. Save
them to our data folder at C:\Program Files\STKR 1.30\Data\"
 

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I responded over there, can't get it to work.


Edit: My computer problem, I had to approve the file change as administrator.

It's fixed and I will reload my tunes shortly.
 

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Charlie don't surf..
'92 Ford Bronco XLT
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14,965 Posts
Discussion Starter #7
he just updated the thread with additional instructions..
 

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Charlie don't surf..
'92 Ford Bronco XLT
Joined
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14,965 Posts
Discussion Starter #8
Before my MAF swap I had a similar problem and tore through my old SD harness looking that resistor and never found anything indicating it was the problem.

Current harness is newer, from a MAF truck and in much better condition than my old one, but I guess it could be the problem. I just really hate to have to start tearing into the harness again..

So, the PIP is on pin 56 and the TFI is on 4. The resistor goes between 4 and the TFI. My TFI is a brand spanking new motorcraft part...Guess it is possible it's bad, will swap in my spare if the problem comes back. Also, wondering if I can use my break out box to check that resistor before tearing apart the harness.

Reset the computer then and see if they reappear.

I chased tfi/dizzy troubles for months once, found out the 22k Ohm resister between the dizzy and eec was bad. I am not saying that is what's with yours just empathizing, sucks sometimes. I found it and fixed it then got a new harness anyway. These rigs are getting old.
 

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Charlie don't surf..
'92 Ford Bronco XLT
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14,965 Posts
Discussion Starter #9
Cleared all the codes in memory and then reloaded my tunes with the checksum update. Ran the engine up to operating temp and the codes didn't pop again, but I still need to take it for a drive.

I'm wondering if the 511 code somehow triggered the other codes, and if so, how? I'd be thrilled if this fixed the problem.
 

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Charlie don't surf..
'92 Ford Bronco XLT
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14,965 Posts
Discussion Starter #10
went for a drive yesterday and everything is working like normal, no codes or strange shifting. The 511 code must have been the root cause of those other codes.
 

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Charlie don't surf..
'92 Ford Bronco XLT
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14,965 Posts
Discussion Starter #11
Bringing my old thread back...haven't been driving the Bronco that much lately, so tonight I cranked it up and let it run up to operating temp. After about 20 or so minutes at idle it started acting like it was going to stall, RPM's would drop and come back up. It never actually stalled and after about 5 minutes of doing that it was idling normal again..strange.

Pulled my old red brick scan tool out and checked the codes..sure enough there was 211 erratic pip..it's either a short in that splice where the drain wire and shielding foil is or a bad PIP sensor..last time I tore apart the harness and couldn't find any shorts, so I doubt that's the culprit Really don't want to do that again..on the other hand replacing the dizzy wouldn't be cheap..

I'm going to reload my tweecer tune like I did before and see what that does..stay tuned.
 

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Charlie don't surf..
'92 Ford Bronco XLT
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14,965 Posts
Discussion Starter #13
yeah, I've been leaning towards doing just that..only everything I read about getting that gear off makes it look like a PITA.

Interesting thing happened today. I reloaded the tune from my tweecer and the code went away. However, when the engine goes into closed loop it did the same thing where it acted like it wanted to stall, but didn't and then finally smoothed out.

the fact that it doesn't keep doing it is what's puzzling..you'd think if it were a bad PIP it would do it all the time and how on earth is that related to the engine going into closed loop??
 

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Charlie don't surf..
'92 Ford Bronco XLT
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14,965 Posts
Discussion Starter #14
Turns out my distributor was completey shot. Pulled the old one and the PIP was rusted to hell and making all kinds of noise when I spun the shaft. I'm sure it had water in there at some point in time. Autozone was the only place that had a new dizzy, the duralast gold for $100..probably not the best quality but it will do for now. Once I got it installed it was amazing how much better the truck ran..Haven't checked, but I'm sure the code is gone. O'Reilly's was the only place that had a replacement PIP in stock so I bought one and rebuilt my old dizzy..unfortunately, I cracked the drive gear when I was putting it back on..
 

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Charlie don't surf..
'92 Ford Bronco XLT
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14,965 Posts
Discussion Starter #16
good call..I saw something about that on the internet, but was in too much of a rush and that's why I cracked the gear...lesson learned...
 

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Charlie don't surf..
'92 Ford Bronco XLT
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14,965 Posts
Discussion Starter #18
PiP ??

Dizzy???



What are those? :scratchhe
a Pip, also know as the distributor pick up is found inside the distributor and is what triggers the ingition system to fire.

Dizzy, shortened form of distributor..:toothless
 
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