Engine missing or timing retarding or ?
Thread Starter
Burning Brakes
Joined: Feb 1999
Posts: 1,157
Likes: 3
From: Encino CA
Engine missing or timing retarding or ?
I have a basically stock LT1 (Hypertech, Grannatelli MAF, K&N, cold air) and there is something I have noticed that happens but mostly on sustained climb at freeway speeds. This came back to mind because the other day, I was on the freeway and hit the grade coming back from Camarillo into the San Fernando Valley (Angelenos will know what I am talking about). I have an automatic and was in overdrive coming into the grade at about 70mph. At the grade, it felt like a missing or timing retard--intermittent reduction of power. If I shift into the standard drive to get the revs up, the car seems fine. Is this a normal consequence of essentially "lugging" the engine while in too low a gear (i.e., overdrive). I wonder if this is the ecm retard kicking in due to knock (the best gas I can get here is now rated 91 octane).
Thread Starter
Burning Brakes
Joined: Feb 1999
Posts: 1,157
Likes: 3
From: Encino CA
Re: Engine missing or timing retarding or ? (C4-Wolf)
No warning lights whenever this has happened. I was wondering if that meant that there were no "codes" to check. Do codes only get "thrown" if you get a warning light? Anyway, this apparent loss of power only seems to happen on moderate long grades at freeway speed while in OD. No lights and all guages seem okay. It almost feels like someone is momentarily disconnecting a spark wire or shutting down the fuel. In the "old" days before computer controls this would have been similar to engine missing but I wonder if what I am feeling is spark retard by the ecm.
Le Mans Master
Joined: Jul 2001
Posts: 6,252
Likes: 2
From: Silicon Valley Kalifornia
Re: Engine missing or timing retarding or ? (DougSilver)
Zero in on the ignition system (assuming fuel system checks out ok, check pressure, replace fuel filter) ....bad spark plug gaping....wires....arcing...cracked cap.
Drifting
Joined: Mar 1999
Posts: 1,931
Likes: 1
From: Norcross GA
Re: Engine missing or timing retarding or ? (DougSilver)
Put a scanner on the ALDL and see what the engine is doing.
This will tell you if the knock sensor is going off, if the TC is unlocking, if....
This will tell you if the knock sensor is going off, if the TC is unlocking, if....
Le Mans Master
Joined: Oct 1999
Posts: 6,366
Likes: 34
Re: Engine missing or timing retarding or ? (DougSilver)
Was this on the camarillo grade or the one in calabasas on the 101?
I found my car was missing at idle, it would fire fine when I reved it up a good bit. Wires looked good, no arcing etc... I decided to pull the wires for the hell of it and one wire snapped right off the boot. it was toasted... I know the LT1 is a nightmare but maybe it is time for new wires?
You mention knocking, could you hear it knocking?
I also had a similar feeling in my car when I had an exhuast leak, but this is on an L98, I only have 1 O2 sensor.
I found my car was missing at idle, it would fire fine when I reved it up a good bit. Wires looked good, no arcing etc... I decided to pull the wires for the hell of it and one wire snapped right off the boot. it was toasted... I know the LT1 is a nightmare but maybe it is time for new wires?
You mention knocking, could you hear it knocking?
I also had a similar feeling in my car when I had an exhuast leak, but this is on an L98, I only have 1 O2 sensor.
Le Mans Master
Joined: Oct 1999
Posts: 6,366
Likes: 34
Re: Engine missing or timing retarding or ? (DougSilver)
No warning lights whenever this has happened. I was wondering if that meant that there were no "codes" to check. Do codes only get "thrown" if you get a warning light?
If the check engine light comes on for a second, there should be a code stored, untill you remove it. Usually by removing battery power for 30-60 seconds, or if you have a scanner capable of clearing codes.
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Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: Engine missing or timing retarding or ? (DougSilver)
Next time it does it, tap the brake pedal momentarily to unlock the torque converter clutch...if it smooth out then comes back about a second later, it is probably the converter clutch getting weak ( it happens ). A little playing around like this with the brake pedal and noticing the effects, you can tell pretty reliably if it is a converter clutch problem or not.
Thread Starter
Burning Brakes
Joined: Feb 1999
Posts: 1,157
Likes: 3
From: Encino CA
Re: Engine missing or timing retarding or ? (BBA)
Bill--it was the long Camarillo grade. The only other time this happened was a couple of years ago while driving on the toll road in Orange County that goes past Aliso Viejo. There is also a long steady grade there that goes on for miles and this problem happened while in overdrive. I had not even considered the torque converter--thanks to those that recommended it. I assume that tapping the brake pedal "unlocks" the lock-up mechanism--I did not know that. I am planning to install some 1.6 roller rockers in the near future and at that time, I should probably also have the plugs and wires replaced. Even if that is not the cause it's about time (40,000 miles).
