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tips, technology, tools and techniques related to vehicle driveline components

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limey222
Michael Cubbon
Portland, OR
(100 posts)

Registered:
08/01/2015 12:55PM

Main British Car:
1969 MGB GM 3.4L V6

To owners of 93-95 GM 3.4 conversions
Posted by: limey222
Date: October 30, 2017 05:11PM

Recently my car has developed an annoying stumble if I let the revs drop too low while lugging around town in 2nd and 3rd. Previously I was always amazed by its low end torque and it would pull away in 2nd and 3rd as long as it was moving forward at the time. Now when i go to accelerate there is a stumble like it is going to stall and almost a misfire before it recovers and accelerate normally. All sensors were replaced just over a year ago. New coil pack and base about 6 months ago. New injectors and fuel regulator valve two months ago. No codes are showing up on my laptop.
Any ideas?



Edited 2 time(s). Last edit at 10/30/2017 05:12PM by limey222.


Scott68B
Scott Costanzo
Columbus, Ohio
(495 posts)

Registered:
10/25/2007 11:30AM

Main British Car:
1968 MGB GM 5.3 LS4 V8

authors avatar
Re: To owners of 93-95 GM 3.4 conversions
Posted by: Scott68B
Date: October 30, 2017 07:09PM

Did you go with the stock flowing injectors or the greater flowing injectors you mentioned you wanted to go with?


limey222
Michael Cubbon
Portland, OR
(100 posts)

Registered:
08/01/2015 12:55PM

Main British Car:
1969 MGB GM 3.4L V6

Re: To owners of 93-95 GM 3.4 conversions
Posted by: limey222
Date: October 30, 2017 09:57PM

OK, Here is what might be considered a strange question. Should the ECM controlling a 94 GM 3.4L engine conversion always be powered up?
The reason I ask this is that I have a hidden, dual pole battery isolation switch installed which disconnects both + and - of my battery.
Got to thinking about this and I need to know if this means that my ECM is having to re-learn every time I drive the car or does it have an internal protected memory for the settings


88v8
Ivor Duarte
Gloucestershire UK
(517 posts)

Registered:
02/11/2010 04:29AM

Main British Car:
1974 Land Rover Lightweight V8

Re: To owners of 93-95 GM 3.4 conversions
Posted by: 88v8
Date: October 31, 2017 05:17AM

Even if it does, these ancillary batteries are not ever-lasting

Ivor


Scott68B
Scott Costanzo
Columbus, Ohio
(495 posts)

Registered:
10/25/2007 11:30AM

Main British Car:
1968 MGB GM 5.3 LS4 V8

authors avatar
Re: To owners of 93-95 GM 3.4 conversions
Posted by: Scott68B
Date: October 31, 2017 05:27AM

It will do a re-learn if you disconnect power from the ECU.


mstemp
Mike Stemp
Calgary, Canada
(180 posts)

Registered:
11/25/2009 07:18AM

Main British Car:
1980 MGB Rover 4.6L

Re: To owners of 93-95 GM 3.4 conversions
Posted by: mstemp
Date: October 31, 2017 07:59AM

Rather than using the disconnect you could,wire in a battery tender. Try that as a test to see if it solves the running issue. I use that on my rover FI V8, only fully disconnecting battery for longer term storage as the ECU has to relearn and caused some poor running for the first few full warmups.


DiDueColpi
Fred Key
West coast - Canada
(1218 posts)

Registered:
05/14/2010 03:06AM

Main British Car:
What if the Hokey Pokey really is what it's all about?

authors avatar
Re: To owners of 93-95 GM 3.4 conversions
Posted by: DiDueColpi
Date: November 06, 2017 12:41PM

Have a look at your MAF Michael.
I'll bet that you have a buildup of contaminants on the sensor elements.
The smallest amount of dirt can throw these MAF's out of range and never produce a fault code.
Over oiled gauze type air filters will also gum up the sensor
Take a small soft artists brush and some carb cleaner to clean up the sensors. Be very gentle as they are fragile.
The difference in running is sometimes dramatic.

Cheers
Fred



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