Hesitating/bucking under load
Thread Starter
Melting Slicks
Joined: Dec 2002
Posts: 2,480
Likes: 62
From: Middletown DE
Hesitating/bucking under load
Been driving the car every chance I get. Romping here and there, everything has seemed fine. The other day I just took the car out to take across town and noticed when lightly accelerating or any load, motor seems to start hesitating and feels like I'm running on 7 cyl.
Worried for the worst, I checked compression on 5 and 7 and they seem fine. 185psi and 175psi. Haven't had the time to check the rest, but shifting my mental focus to coil or wires.
Is there a process to test the coils? Or anything else I should be looking at here?
Thanks, John.
Worried for the worst, I checked compression on 5 and 7 and they seem fine. 185psi and 175psi. Haven't had the time to check the rest, but shifting my mental focus to coil or wires.
Is there a process to test the coils? Or anything else I should be looking at here?
Thanks, John.
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
If you have MSD wires, pull them all. Get a good meter and test the resistance. They should all be less than 31 ohms. Even if they're brand new, I test them and have had them measure 4000 ohms out of the box. Any time you put them back on, put dielectric grease in the spark plug boot, but never the coil boot.
Any high resistance wire, send them in for warranty replacement.
I haven't had this trouble with GM wires, but it's worth a check while you're in there.
Any high resistance wire, send them in for warranty replacement.
I haven't had this trouble with GM wires, but it's worth a check while you're in there.
Melting Slicks
Joined: Jun 2012
Posts: 3,163
Likes: 6
From: Oceanside California
Try unpluging one coil at a time and see if there's one that doesn't make a change in the way it's running. Easier than pulling plugs off the bat. If it does't work, I'd start by changing plugs. They can partially work, and fail at higher rpm if slightly damaged.
Burning Brakes
Joined: Dec 2003
Posts: 1,243
Likes: 5
From: Loveland CO
do you have any way to scan the car? might be KR you are feeling. if its a misfire you should be a code for a misfire or at least get a misfire count in the scanning software. Anyone who mods there cars should have a way to scan the car IMHO..
* Scan the car for misfires and Knock retard
* Check fuel pressure
* inspect plugs/wires & Replace as needed
* finish compression tests an on all cyl. (i bet you will be fine, #7 is usually the problem hole)
S
* Scan the car for misfires and Knock retard
* Check fuel pressure
* inspect plugs/wires & Replace as needed
* finish compression tests an on all cyl. (i bet you will be fine, #7 is usually the problem hole)
S
Thread Starter
Melting Slicks
Joined: Dec 2002
Posts: 2,480
Likes: 62
From: Middletown DE
Thanks guys.
I left out the details of my semi recent (last year) coil relocation where I placed the wires under the headers.
Upon checking compression, I see the clips I used to manage the wires have deformed under the heat (bad purchase obviously) and #1 wire was laying on the header. Did not think much of it, as wire seemed fine.
I'll get that off the header and take it for a quick spin before diving into coil check.
Thanks guys, needed a sanity check here.
On vaca now, so I'll check when I get back and report in.
John
I left out the details of my semi recent (last year) coil relocation where I placed the wires under the headers.
Upon checking compression, I see the clips I used to manage the wires have deformed under the heat (bad purchase obviously) and #1 wire was laying on the header. Did not think much of it, as wire seemed fine.
I'll get that off the header and take it for a quick spin before diving into coil check.
Thanks guys, needed a sanity check here.
On vaca now, so I'll check when I get back and report in.
John
Thread Starter
Melting Slicks
Joined: Dec 2002
Posts: 2,480
Likes: 62
From: Middletown DE
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