misfire, knock, surging rpms
Thread Starter
On The Tree
Joined: Jun 2007
Posts: 166
Likes: 0
From: Birmingham, Alabama
misfire, knock, surging rpms Well, my 94z is having some problems....I noticed the other day that the rpms were surging up and down from about 1500 to 1800. It would go back and forth but was only when I let completely off the gas. For about a month now, I have thought that it has been having a little rough idle. The rpm's dont jump around much(but will a hair) and there is a vibration that doesnt feel like it should be there.
Tonight on the way home from work, if I punched the gas or tried to accelerate hard, the engine would knock and almost die. It is fine if you are just cruising along and slowly raise the rpms and was fine just cruising. Any advice or what this could be?
Newly built tranny
93 octane gas
automatic
replaced spark plugs about 3,000 miles ago(but not sure if the guy did all 8 or not....he should have seeing as how I gave him 8 plugs.
but:I didn't replace spark plug wires
Tonight on the way home from work, if I punched the gas or tried to accelerate hard, the engine would knock and almost die. It is fine if you are just cruising along and slowly raise the rpms and was fine just cruising. Any advice or what this could be?
Newly built tranny
93 octane gas
automatic
replaced spark plugs about 3,000 miles ago(but not sure if the guy did all 8 or not....he should have seeing as how I gave him 8 plugs.
but:I didn't replace spark plug wires
It could be any number of things at this point. Did the problem exist before you had the plugs put in? Is it setting any codes? Make sure all you're sensors are pluged in and the plug wires are on the correct plugs. You might also check you're fuel pressure.
Good Luck!
Good Luck!
Thread Starter
On The Tree
Joined: Jun 2007
Posts: 166
Likes: 0
From: Birmingham, Alabama
I never noticed the problem before the plugs were changed...but the roughness could be because I put poly engine and trans mounts...but the stumbling under hard acceleration wasnt there until last night....still there this morning!
TECH Enthusiast
Joined: Feb 2003
Posts: 675
Likes: 0
From: Longview, TX
well, hmm, i worked for a dealership, so we could check them with a scan tool to see what it was trying to do and what it was accually doing.
let me think for a minute and get back to you...
let me think for a minute and get back to you...
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Verdad Gallardo According to a Haynes maunal once you unplug the IAC the computer will have to relearn the Engine idle speed, this may take a few minutes. The maunal says how to check the ohms on the IAC and TPS.
On the missing, it's possibly a bad plug(s), if they were rough with them on the install a few heat cycles may have cracked a plug(s). When I rebuilt my motor I put in new plugs and my wires were only about 6 months old. I had two dead cylinders! I replaced the plugs and wires and it fixed the problem. However mine didn't miss or cutout it just lacked bottom end power. It did have an unusual vibration at around 3500 rpm.
How's fuel psi, filter?
I'm just guessing, Good Luck!
On the missing, it's possibly a bad plug(s), if they were rough with them on the install a few heat cycles may have cracked a plug(s). When I rebuilt my motor I put in new plugs and my wires were only about 6 months old. I had two dead cylinders! I replaced the plugs and wires and it fixed the problem. However mine didn't miss or cutout it just lacked bottom end power. It did have an unusual vibration at around 3500 rpm.
How's fuel psi, filter?
I'm just guessing, Good Luck!
