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All,
I wonder if you can provide some advice on troubleshooting a
progressive issue with my 1978 MGB – sporadic engine hiccupping/roughness.
I think I mentioned before that over the last several
years there is a sporadic engine hiccup.
Typically, this happened only when the engine is thoroughly warned up
and when lugging the engine such as when coming out of a tight turn at low
speed in too high a gear. Now it’s
happening quiet a lot and the engine has begun missing for several seconds when
cruising at road speeds.
Background information
-
A couple weeks ago I drove a the rally on a
warm day with a fair bit of stop-and-go traffic and experienced the hiccupping many
times but no sustained roughness.
-
Today on cool temperatures, I went 50 miles
with a mix of driving with hiccupping only a few times and one episode of roughness
for several seconds while cruising (45 MPH).
- I have electronic ignition, I think Petronix, about 15
years old – replaced when car restored around 2006 and engine rebuilt.
- Sustained roughness feels similar to when one
cylinder has a stuck valve (experienced this 25,000 miles ago right after
engine rebuild).
-
New contactless fuel pump installed seven or
eight years ago.
-
I typically use Sunoco Ultra 93 gas.
Troubling shooting so far.
-
Engine starts easily and runs smoothly when not
hiccupping/missing. Slight miss at idle.
-
At high speed (75+ MPH) and sustained full throttle runs
smoothly so likely not fuel starvation.
-
Checked appearance of spark plugs. All look good and alike with slight carboning and no
oil.
-
Replaced leads from distributor to plugs and
coil. The old leads had resistances from
300 to 400 ohms, The new ones 500 to 700
ohms. Problem continues.
Any suggestions you can make on troubleshooting to isolate
the problem will be appreciated.
Thanks,
Roger S.
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|
Hey Roger,
I had some symptoms similar to yours when I got my current B. It ended up being the electronic ignition. I refreshed it with a petronix and it worked well again.
YMMV... Kenn Brown
RS282284
CHRISTIE'S International Real Estate
Long & Foster Devon
All,
I wonder if you can provide some advice on troubleshooting a
progressive issue with my 1978 MGB – sporadic engine hiccupping/roughness.
I think I mentioned before that over the last several
years there is a sporadic engine hiccup.
Typically, this happened only when the engine is thoroughly warned up
and when lugging the engine such as when coming out of a tight turn at low
speed in too high a gear. Now it’s
happening quiet a lot and the engine has begun missing for several seconds when
cruising at road speeds.
Background information
-
A couple weeks ago I drove a the rally on a
warm day with a fair bit of stop-and-go traffic and experienced the hiccupping many
times but no sustained roughness.
-
Today on cool temperatures, I went 50 miles
with a mix of driving with hiccupping only a few times and one episode of roughness
for several seconds while cruising (45 MPH).
- I have electronic ignition, I think Petronix, about 15
years old – replaced when car restored around 2006 and engine rebuilt.
- Sustained roughness feels similar to when one
cylinder has a stuck valve (experienced this 25,000 miles ago right after
engine rebuild).
-
New contactless fuel pump installed seven or
eight years ago.
-
I typically use Sunoco Ultra 93 gas.
Troubling shooting so far.
-
Engine starts easily and runs smoothly when not
hiccupping/missing. Slight miss at idle.
-
At high speed (75+ MPH) and sustained full throttle runs
smoothly so likely not fuel starvation.
-
Checked appearance of spark plugs. All look good and alike with slight carboning and no
oil.
-
Replaced leads from distributor to plugs and
coil. The old leads had resistances from
300 to 400 ohms, The new ones 500 to 700
ohms. Problem continues.
Any suggestions you can make on troubleshooting to isolate
the problem will be appreciated.
Thanks,
Roger S.
|
|
|
Kevin McLemore
Yeah, I'm with Kenn. It sounds a lot like ignition, as we discussed earlier. I'd replace the distributor temporarily with an original points distributor and see how it runs... if it's good then you can either replace the Pertronix or go with original. There
are plenty of good used dizzys around to use temporarily.
toggle quoted message
Show quoted text
From: PhillyMGClub@groups.io <PhillyMGClub@groups.io> on behalf of Kenn & Kathy Brown <oldmainlinehomes@...>
Sent: Saturday, June 18, 2022 6:55 PM
To: Philly Mg club <PhillyMGClub@groups.io>
Subject: Re: [PhillyMGClub] Suggestions on Troubleshooting
Hey Roger,
I had some symptoms similar to yours when I got my current B. It ended up being the electronic ignition. I refreshed it with a petronix and it worked well again.
YMMV...
Kenn
Brown
RS282284
CHRISTIE'S International Real Estate
Long & Foster Devon
All,
I wonder if you can provide some advice on troubleshooting a progressive issue with my 1978 MGB – sporadic engine hiccupping/roughness.
I think I mentioned before that over the last several years there is a sporadic engine hiccup. Typically, this happened only when the engine is thoroughly warned up and when lugging the engine such as when coming out of a tight turn
at low speed in too high a gear. Now it’s happening quiet a lot and the engine has begun missing for several seconds when cruising at road speeds.
Background information
-
A couple weeks ago I drove a the rally on a warm day with a fair bit of stop-and-go traffic and experienced the hiccupping many times but no sustained roughness.
-
Today on cool temperatures, I went 50 miles with a mix of driving with hiccupping only a few times and one episode of roughness for several seconds while cruising (45 MPH).
- I have electronic ignition, I think Petronix, about
15 years old – replaced when car restored around 2006 and engine rebuilt.
- Sustained roughness feels similar to when one cylinder
has a stuck valve (experienced this 25,000 miles ago right after engine rebuild).
-
New contactless fuel pump installed seven or eight years ago.
-
I typically use Sunoco Ultra 93 gas.
Troubling shooting so far.
-
Engine starts easily and runs smoothly when not hiccupping/missing. Slight miss at idle.
-
At high speed (75+ MPH) and sustained full throttle runs smoothly so likely not fuel starvation.
-
Checked appearance of spark plugs. All look good and alike with slight carboning and no oil.
-
Replaced leads from distributor to plugs and coil. The old leads had resistances from 300 to 400 ohms, The new ones 500 to 700 ohms. Problem continues.
Any suggestions you can make on troubleshooting to isolate the problem will be appreciated.
Thanks,
Roger S.
|
|
|
Sounds like the ignition coil is failing. The key symptom is that it is worse when hot.
Ira
On Jun 18, 2022, at 7:04 PM, Kevin McLemore <kmclemore@...> wrote:
Yeah, I'm with Kenn. It sounds a lot like ignition, as we discussed earlier. I'd replace the distributor temporarily with an original points distributor and see how it runs... if it's good then you can either replace the Pertronix or go with original. There
are plenty of good used dizzys around to use temporarily.
From: PhillyMGClub@groups.io <PhillyMGClub@groups.io> on behalf of Kenn & Kathy Brown <oldmainlinehomes@...>
Sent: Saturday, June 18, 2022 6:55 PM
To: Philly Mg club <PhillyMGClub@groups.io>
Subject: Re: [PhillyMGClub] Suggestions on Troubleshooting
Hey Roger,
I had some symptoms similar to yours when I got my current B. It ended up being the electronic ignition. I refreshed it with a petronix and it worked well again.
YMMV...
Kenn
Brown
RS282284
CHRISTIE'S International Real Estate
Long & Foster Devon
All,
I wonder if you can provide some advice on troubleshooting a progressive issue with my 1978 MGB – sporadic engine hiccupping/roughness.
I think I mentioned before that over the last several years there is a sporadic engine hiccup. Typically, this happened only when the engine is thoroughly warned up and when lugging the engine such as when coming out of a tight turn
at low speed in too high a gear. Now it’s happening quiet a lot and the engine has begun missing for several seconds when cruising at road speeds.
Background information
-
A couple weeks ago I drove a the rally on a warm day with a fair bit of stop-and-go traffic and experienced the hiccupping many times but no sustained roughness.
-
Today on cool temperatures, I went 50 miles with a mix of driving with hiccupping only a few times and one episode of roughness for several seconds while cruising (45 MPH).
- I have electronic ignition, I think Petronix, about
15 years old – replaced when car restored around 2006 and engine rebuilt.
- Sustained roughness feels similar to when one cylinder
has a stuck valve (experienced this 25,000 miles ago right after engine rebuild).
-
New contactless fuel pump installed seven or eight years ago.
-
I typically use Sunoco Ultra 93 gas.
Troubling shooting so far.
-
Engine starts easily and runs smoothly when not hiccupping/missing. Slight miss at idle.
-
At high speed (75+ MPH) and sustained full throttle runs smoothly so likely not fuel starvation.
-
Checked appearance of spark plugs. All look good and alike with slight carboning and no oil.
-
Replaced leads from distributor to plugs and coil. The old leads had resistances from 300 to 400 ohms, The new ones 500 to 700 ohms. Problem continues.
Any suggestions you can make on troubleshooting to isolate the problem will be appreciated.
Thanks,
Roger S.
|
|
|
Ira,
I think you may be right on the coil. I remember when installing my petronix on the B that there was some discussions on the forums about using a particular range of coil due to failures.
Kenn
Kenn Brown RS282284 CHRISTIE'S International Real Estate CNE , SSC Certified Relocation Agent OICP (Investment Certification program)Long and Foster Real Estate92 Lancaster Ave., Devon, PA 19333cell: 610.585.0011 www.oldmainlinehomes.com
On Sat, Jun 18, 2022 at 9:59 PM Ira Spector < spectors4@...> wrote:
Sounds like the ignition coil is failing. The key symptom is that it is worse when hot.
Ira
On Jun 18, 2022, at 7:04 PM, Kevin McLemore <kmclemore@...> wrote:
Yeah, I'm with Kenn. It sounds a lot like ignition, as we discussed earlier. I'd replace the distributor temporarily with an original points distributor and see how it runs... if it's good then you can either replace the Pertronix or go with original. There
are plenty of good used dizzys around to use temporarily.
Hey Roger,
I had some symptoms similar to yours when I got my current B. It ended up being the electronic ignition. I refreshed it with a petronix and it worked well again.
YMMV...
Kenn
Brown
RS282284
CHRISTIE'S International Real Estate
Long & Foster Devon
All,
I wonder if you can provide some advice on troubleshooting a progressive issue with my 1978 MGB – sporadic engine hiccupping/roughness.
I think I mentioned before that over the last several years there is a sporadic engine hiccup. Typically, this happened only when the engine is thoroughly warned up and when lugging the engine such as when coming out of a tight turn
at low speed in too high a gear. Now it’s happening quiet a lot and the engine has begun missing for several seconds when cruising at road speeds.
Background information
-
A couple weeks ago I drove a the rally on a warm day with a fair bit of stop-and-go traffic and experienced the hiccupping many times but no sustained roughness.
-
Today on cool temperatures, I went 50 miles with a mix of driving with hiccupping only a few times and one episode of roughness for several seconds while cruising (45 MPH).
- I have electronic ignition, I think Petronix, about
15 years old – replaced when car restored around 2006 and engine rebuilt.
- Sustained roughness feels similar to when one cylinder
has a stuck valve (experienced this 25,000 miles ago right after engine rebuild).
-
New contactless fuel pump installed seven or eight years ago.
-
I typically use Sunoco Ultra 93 gas.
Troubling shooting so far.
-
Engine starts easily and runs smoothly when not hiccupping/missing. Slight miss at idle.
-
At high speed (75+ MPH) and sustained full throttle runs smoothly so likely not fuel starvation.
-
Checked appearance of spark plugs. All look good and alike with slight carboning and no oil.
-
Replaced leads from distributor to plugs and coil. The old leads had resistances from 300 to 400 ohms, The new ones 500 to 700 ohms. Problem continues.
Any suggestions you can make on troubleshooting to isolate the problem will be appreciated.
Thanks,
Roger S.
|
|
|
Try the higher voltage sports coil. I’ve had the same symptoms in my MGB, and it was the coil.
Ira
On Jun 18, 2022, at 10:05 PM, Kenn & Kathy Brown <oldmainlinehomes@...> wrote:
Ira,
I think you may be right on the coil.
I remember when installing my petronix on the B that there was some discussions on the forums about using a particular range of coil due to failures.
Kenn
Kenn Brown RS282284
CHRISTIE'S International Real Estate
CNE , SSC
Certified Relocation Agent OICP (Investment Certification program)
Long and Foster Real Estate
92 Lancaster Ave., Devon, PA 19333
cell: 610.585.0011 www.oldmainlinehomes.com
On Sat, Jun 18, 2022 at 9:59 PM Ira Spector < spectors4@...> wrote:
Sounds like the ignition coil is failing. The key symptom is that it is worse when hot.
Ira
On Jun 18, 2022, at 7:04 PM, Kevin McLemore <kmclemore@...> wrote:
Yeah, I'm with Kenn. It sounds a lot like ignition, as we discussed earlier. I'd replace the distributor temporarily with an original points distributor and see how it runs... if it's good then you can either replace the Pertronix or go with original. There
are plenty of good used dizzys around to use temporarily.
Hey Roger,
I had some symptoms similar to yours when I got my current B. It ended up being the electronic ignition. I refreshed it with a petronix and it worked well again.
YMMV...
Kenn
Brown
RS282284
CHRISTIE'S International Real Estate
Long & Foster Devon
All,
I wonder if you can provide some advice on troubleshooting a progressive issue with my 1978 MGB – sporadic engine hiccupping/roughness.
I think I mentioned before that over the last several years there is a sporadic engine hiccup. Typically, this happened only when the engine is thoroughly warned up and when lugging the engine such as when coming out of a tight turn at low speed in too
high a gear. Now it’s happening quiet a lot and the engine has begun missing for several seconds when cruising at road speeds.
Background information
-
A couple weeks ago I drove a the rally on a warm day with a fair bit of stop-and-go traffic and experienced the hiccupping many times but no sustained roughness.
-
Today on cool temperatures, I went 50 miles with a mix of driving with hiccupping only a few times and one episode of roughness for several seconds while cruising (45 MPH).
- I have electronic ignition, I think Petronix, about
15 years old – replaced when car restored around 2006 and engine rebuilt.
- Sustained roughness feels similar to when one cylinder
has a stuck valve (experienced this 25,000 miles ago right after engine rebuild).
-
New contactless fuel pump installed seven or eight years ago.
-
I typically use Sunoco Ultra 93 gas.
Troubling shooting so far.
-
Engine starts easily and runs smoothly when not hiccupping/missing. Slight miss at idle.
-
At high speed (75+ MPH) and sustained full throttle runs smoothly so likely not fuel starvation.
-
Checked appearance of spark plugs. All look good and alike with slight carboning and no oil.
-
Replaced leads from distributor to plugs and coil. The old leads had resistances from 300 to 400 ohms, The new ones 500 to 700 ohms. Problem continues.
Any suggestions you can make on troubleshooting to isolate the problem will be appreciated.
Thanks,
Roger S.
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