ECM surprise ????
Thread Starter
Burning Brakes
Joined: Feb 2013
Posts: 769
Likes: 95
From: Central Pennsylvania
ECM surprise ????
Today, while browsing around under the hood of my newest addition, a 1991 convertible, I noticed that the ECM was a replacement. No problem, the PO told me he had replaced it. Well, it appeared very loose in the mounting, so I further loosened it to check the mounting bracket. When I moved the unit I heard something rattling around inside. I removed the chip access screws and saw a loose, blue item.
Huh??? I removed it and here it is.
Car runs, is it an old prom or what ? Should it be attached to something ?
Beyond my pay grade
Huh??? I removed it and here it is.
Car runs, is it an old prom or what ? Should it be attached to something ?
Beyond my pay grade
Racer
Joined: Dec 2014
Posts: 402
Likes: 44
From: Pittsburgh PA
Well it is definitely the prom/memcal chip. According to the BBC AXCR it is for a 91 L98 automatic with a 2.59 rear end. My question is do you have another prom plugged in to the circuit board? Can you post a pic of the opening under the ECM?
Ken
Ken
Melting Slicks
Joined: Sep 2010
Posts: 2,422
Likes: 202
that is a traditional & original speed density prom carrier. worth GOLD!! I'm sure you will find a aftermarket worthless!! SHELF tune prom carrier inside. open the ECM cover and reveal your surprise!!
Last edited by THE 383 admiral; Aug 2, 2016 at 02:34 PM.
Thread Starter
Burning Brakes
Joined: Feb 2013
Posts: 769
Likes: 95
From: Central Pennsylvania
Seems to me that there has to be a prom plugged in. Wouldn't start or run without it
Coincidentally, SES light came on. Looks like a D45.
(need to locate a cluster without missing segments)
Here's what's inside the ECM :
Coincidentally, SES light came on. Looks like a D45.
(need to locate a cluster without missing segments)Here's what's inside the ECM :
Last edited by skyhawk50; Aug 2, 2016 at 04:05 PM.
Racer
Joined: Dec 2014
Posts: 402
Likes: 44
From: Pittsburgh PA
Thread Starter
Burning Brakes
Joined: Feb 2013
Posts: 769
Likes: 95
From: Central Pennsylvania
Here what you have.
http://www.moates.net/g1-memory-adap...-etc-p-32.html
http://www.moates.net/g1-memory-adap...-etc-p-32.html
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Racer
Joined: Dec 2014
Posts: 402
Likes: 44
From: Pittsburgh PA
Racer
Joined: Dec 2014
Posts: 402
Likes: 44
From: Pittsburgh PA
Thread Starter
Burning Brakes
Joined: Feb 2013
Posts: 769
Likes: 95
From: Central Pennsylvania
I believe I got the problem solved. I removed the Moates adapter and plugged the OEM chip back in by itself. SES light did not come on, car runs great again, no rich exhaust smell, no stumbling on acceleration. NO codes set.
Sooooooo, the OEM chip plugged into the Moates adapter? I believe I got a LOT to learn !!!
Ya gotta love the C4. ( still my favorite ) At 65 years old, I doubt I'll buy anything newer, such as a C5, C6, and especially a C7. (I'd rather own 2 or 3 C4's instead of a single C5)
Thanks for all the great input. If anyone's in Carlisle next month, I'll be either directing cars in the parking area or loafing at my club canopy, Central PA Corvette Club, by the Subway Sub stand.
Sooooooo, the OEM chip plugged into the Moates adapter? I believe I got a LOT to learn !!!
Ya gotta love the C4. ( still my favorite ) At 65 years old, I doubt I'll buy anything newer, such as a C5, C6, and especially a C7. (I'd rather own 2 or 3 C4's instead of a single C5)
Thanks for all the great input. If anyone's in Carlisle next month, I'll be either directing cars in the parking area or loafing at my club canopy, Central PA Corvette Club, by the Subway Sub stand.
Last edited by skyhawk50; Aug 2, 2016 at 07:21 PM.
Racer
Joined: Dec 2014
Posts: 402
Likes: 44
From: Pittsburgh PA
Good to hear everything is back to normal. I got my first corvette (1990) at age 60. Over the last 2 years I have learned a lot while restoring it. I went the NCRS route and this past June achieved Top Flight at the local NCRS chapter. Looking towards the regional flight judging net year.
Enjoy
Enjoy
Melting Slicks
Joined: Sep 2010
Posts: 2,422
Likes: 202
NO one noticed?? with the specific MOATES adapter that was installed in your 90 - 93 ECM
was in fact designed to MOD a 89 and below Prom carrier. TAKE note inside of your 91 prom carrier. there is actually a daughterboard that contains your KNOCK sensor. WHO ever did this MOD was clueless. your knock senor was OUT of service. post 11 has the proper adapter that should have been used!
was in fact designed to MOD a 89 and below Prom carrier. TAKE note inside of your 91 prom carrier. there is actually a daughterboard that contains your KNOCK sensor. WHO ever did this MOD was clueless. your knock senor was OUT of service. post 11 has the proper adapter that should have been used!
Last edited by THE 383 admiral; Aug 3, 2016 at 10:04 AM.
Thread Starter
Burning Brakes
Joined: Feb 2013
Posts: 769
Likes: 95
From: Central Pennsylvania
NO one noticed?? with the specific MOATES adapter that was installed in your 90 - 93 ECM
was in fact designed to MOD a 89 and below Prom carrier. TAKE note inside of your 91 prom carrier. there is actually a doughterboard that contains your KNOCK sensor. WHO ever did this MOD was clueless. your knock senor was OUT of service. post 11 has the proper adapter that should have been used!
was in fact designed to MOD a 89 and below Prom carrier. TAKE note inside of your 91 prom carrier. there is actually a doughterboard that contains your KNOCK sensor. WHO ever did this MOD was clueless. your knock senor was OUT of service. post 11 has the proper adapter that should have been used!
And his son did a real "hack job" of an aftermarket radio install.
EG- he ran a constant 12v from the battery to the radio for memory retention. There was one about 2 inches from the radio in the original harness....Duh!!!!
I'm still dealing with the headlights that pop up when park lights activated. They don't illuminate until headlight switch is turned to headlight position. All wires to headlight switch are in correct positions, relay for headlight buckets seem normal. Maybe a wire was cut under the dash ????? Maybe part of his search for power for the radio ????? Who knows ???
Sorry for the long-winded rant. This is what happens when one retires and has too much time on their hands. LOL
Melting Slicks
Joined: Sep 2010
Posts: 2,422
Likes: 202
Doesn't surprise me. I've been discovering other half a$$ed work done to this car. Too bad stupidity isn't painful. Oh well, it's in good hands now! The PO's "Vette expert mechanic" cut a few other corners.
And his son did a real "hack job" of an aftermarket radio install.
EG- he ran a constant 12v from the battery to the radio for memory retention. There was one about 2 inches from the radio in the original harness....Duh!!!!
I'm still dealing with the headlights that pop up when park lights activated. They don't illuminate until headlight switch is turned to headlight position. All wires to headlight switch are in correct positions, relay for headlight buckets seem normal. Maybe a wire was cut under the dash ????? Maybe part of his search for power for the radio ????? Who knows ???
Sorry for the long-winded rant. This is what happens when one retires and has too much time on their hands. LOL
And his son did a real "hack job" of an aftermarket radio install.
EG- he ran a constant 12v from the battery to the radio for memory retention. There was one about 2 inches from the radio in the original harness....Duh!!!!
I'm still dealing with the headlights that pop up when park lights activated. They don't illuminate until headlight switch is turned to headlight position. All wires to headlight switch are in correct positions, relay for headlight buckets seem normal. Maybe a wire was cut under the dash ????? Maybe part of his search for power for the radio ????? Who knows ???
Sorry for the long-winded rant. This is what happens when one retires and has too much time on their hands. LOL
Racer
Joined: Dec 2014
Posts: 402
Likes: 44
From: Pittsburgh PA
this is GREAT. you took the vette from such "HACKS" ohhh NO yet another radio / stereo "expert"??? this is a common nightmare with stereo installs. DO yourself a favor! take the radio & related out. and bring the wiring back to OE condition if possible?? it's sad! not hard work at all. yet a VERY high percentage of issue's are related to the stereo HACK experts!
Last edited by kenpeindl; Aug 3, 2016 at 10:50 AM.
Thread Starter
Burning Brakes
Joined: Feb 2013
Posts: 769
Likes: 95
From: Central Pennsylvania
Well, the OEM chip has been in without the upgraded adapter. Car runs great, gonna leave it that way. Moates adapter resting comfortably in my tool box.
Last edited by skyhawk50; Aug 7, 2016 at 09:35 PM.