buckling when under load

fordtech28 · Nov 20, 2007

My cobra has been buckling under load the past two weeks and I've tried to solved this problem the past week and I found two things.One two of my spark plug wires were glowing and arcing these are ford racing wires and they are only 7 months old which I'm mad about .Second my coil for some reason is flashing from the sides of the coil between the metal square around the coil when I accelerate the car and I can see flash marks on the coil but the weired thing is that I have two other coils and they do the same thing and I dont think they are supposed to do that one of the those coil is the original one which was good I just upgraded to a MSD one and the other is a friends that we removed from his car to upgrade it but was working fine.So I'm at a lost why these coils are flashing from the sides any ideas?

Chythar · Nov 20, 2007

The flashing from the coil is the electricity from the coil jumping to the nearest ground. Electricity takes the path of least resistance, so it's now harder for the electricity to get to the spark plugs than it is to jump through the air and ground out through the engine block. When was the last time you checked the cap & rotor on the distributor? If the contacts are corroded, that could be your problem.

The coil wire could be the problem as well. See if your buddy will let you borrow his coil wire as a test, and see if the coil is still arching to the bracket. If you want to go this far, borrow his cap, rotor and spark plug wires too.

I don't think this is the issue, but you may want to check the engine block ground. You should have a wire reaching from the driver's motor mount bolt on the block, over to the frame on that side. I'd make sure the connections are tight and aren't corroded.

Do you have any other electrical issues with the Cobra? Any gauge issues, battery dying, etc?

HISSIN50 · Nov 20, 2007

What plug gaps do you run?

fordtech28 · Nov 20, 2007

The cap and rotor were replaced at the same time as the wires which is leading me to believe I have a bad set of wires since chytar is right about the wire resistance I run .50 gap and been running it like that since I got the car with no issues

fordtech28 · Nov 21, 2007

Chythar said:
The flashing from the coil is the electricity from the coil jumping to the nearest ground. Electricity takes the path of least resistance, so it's now harder for the electricity to get to the spark plugs than it is to jump through the air and ground out through the engine block. When was the last time you checked the cap & rotor on the distributor? If the contacts are corroded, that could be your problem.

The coil wire could be the problem as well. See if your buddy will let you borrow his coil wire as a test, and see if the coil is still arching to the bracket. If you want to go this far, borrow his cap, rotor and spark plug wires too.

I don't think this is the issue, but you may want to check the engine block ground. You should have a wire reaching from the driver's motor mount bolt on the block, over to the frame on that side. I'd make sure the connections are tight and aren't corroded.

Do you have any other electrical issues with the Cobra? Any gauge issues, battery dying, etc?

I put a extra thick ground cable a couple of months ago just because the old one looked bad everything else on the car works 100 percent except for this problem I changed the wires same result I'm going to double check the gap and change out the cap and rotor since I notice all the contacts were almost black and its has copper tops and the coil contact moves around so hopefully thats it

fordtech28 · Nov 26, 2007

UPDATE 11/26/07

The problem turned out to be the autolite spark plugs.This is the second set that has given me problems and they are under 6,000 miles used .I replaced them with motorcrafts which have last me more than 10,000 miles and the car was instantly better and my gas mileage got way better I was getting around 13-14 mpg since I put them on I averaged 16-19 mpg with the motorcrafts.I will never put autolite spark plugs in my car again

revedup · Apr 22, 2008

sPARK PLUGS

ASF 42C's Motorcrafts
i was wondering how long are these supposed tp last?
How many miles you guys been getting.
I heard 25,000 miles is bout right.
got 17,000 miles on them now .
no issues.
what can you guys say bout this

HISSIN50 · Apr 22, 2008

revedup said:
ASF 42C's Motorcrafts
i was wondering how long are these supposed tp last?
How many miles you guys been getting.
I heard 25,000 miles is bout right.
got 17,000 miles on them now .
no issues.
what can you guys say bout this

As long as they don't break or suffer too much gap erosion, they can last quite awhile. I've run coppers for 50K miles before and I've seen them go over 100K before the gap erosion became so great that a miss developed.

I like to change or atleast inspect them every 30K or so.

revedup · Apr 23, 2008

Maintenance from Haynes

This manual calls for 12,000 mile change for plugs and fuel filter!!
Wat can u guys say bout that???

HISSIN50 · Apr 23, 2008

revedup said:
This manual calls for 12,000 mile change for plugs and fuel filter!!
Wat can u guys say bout that???

What manual are you reading?

The O.G. · Apr 23, 2008

what autolites were u using

Zero_chance · Apr 25, 2008

I had autolite 25s in my 88 for two years before I did a head gasket and intake seal job. Replaced them just because I had the heads off but the ones I took out looked fine. The new 25s lasted another two years till I sold it and who knows how much longer.

BlackVert · Apr 25, 2008

do you have one of those cold air intakes with a 90 degree bend in front of the maf?

94' Five.0 · Apr 25, 2008

BlackVert said:
do you have one of those cold air intakes with a 90 degree bend in front of the maf?

Ok this sparked my curiosity. Are you saying this could cause these kind of symptoms?

Chythar · Apr 25, 2008

Absolutely. The sampling tube in the MAF presumes the air is flowing evenly through, so it can reliably do the math and know exactly how much air is flowing. The 90 degree bend cause the air to flow unevenly through the MAF, so there is either more or less air flowing in the engine than the computer thinks there is. That'll cause the engine to run rich or lean, depending on how the readings are off.

You can sometimes rotate the MAF in the tube to improve the calculations. If the MAF happens to be in the right spot to get a proper air sample, the car will run right again.

hollywoodstang · Apr 26, 2008

Chythar said:
Absolutely. The sampling tube in the MAF presumes the air is flowing evenly through, so it can reliably do the math and know exactly how much air is flowing. The 90 degree bend cause the air to flow unevenly through the MAF, so there is either more or less air flowing in the engine than the computer thinks there is. That'll cause the engine to run rich or lean, depending on how the readings are off.

You can sometimes rotate the MAF in the tube to improve the calculations. If the MAF happens to be in the right spot to get a proper air sample, the car will run right again.

Is there special mustang school??? how you guys know all this. 90* pipe will cause air to flow unevenly? even the bend is smooth?

HISSIN50 · Apr 26, 2008

hollywoodstang said:
Is there special mustang school??? how you guys know all this. 90* pipe will cause air to flow unevenly? even the bend is smooth?

It's simple fluid dynamics.

buckling when under load

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