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Strange Hesitation/Sputtering Issue. 78 Z


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I just got my 1978 Z back yesterday. Brand new 6-1 Header, MSA Exhaust, 6 brand new injectors with brand new pig tails, new MSD Ignition coil, Throttle body and IM were cleaned on the inside, EGR system was removed and welded shut.

 

The Car starts and idles fine, but as soon as I get on it in 1st it will sputter and hesitate like a fuel cutout almost and then kick back in. I have only driven it at 3-5 minutes clips at a time and it tends to happen once or twice in that driving period. I am checking my TPS now, which I can only assume is the issue (that or contaminated gas, or maybe a bad fuel pump?) If that's the problem, I am picking up a 1976 Z today with a brand new fuel pump in it so I'll just take that one).

 

It seems to rev up fine and has plenty of power, but this sputtering/ cut out makes me nervous. I could be doing 15-20 in 1st with my foot on the gas and it will sputter, backfire a bit, will stop revving and slow down, but then kick back in 1-3 seconds later. Anyone have any ideas?

 

Also, my car still has a very slight misfire, and I just can't figure out what the hell it is.

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Sounds like your TPS is shorted out. The idle position in the switch also causes a VERY nasty fuel cut rev limit at about the rpm range it seems like you're in.

 

Hmm ok I'll keep that in mind, I think I have 3 or 4 extra TPS laying around somewhere. I just adjusted my TPS, idle now seems perfect at 850, no more backfires through the intake, still a slight backfire at higher revs through the exhaust. I have not driven it yet but will update when I do. If anyone is in the North NJ area who could help me I would greatly appreciate it. I have had the car a few months now and am dying to drive it around without the fear of it leaving me stranded somewhere.

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Just took her out after adjusting the TPS. Was fine at first got through 1-3 fine, turned around on a side street, came back out after a dead stop, gave it gas in first and it began to sputter again like it was going to die, it bucked a bit, I pulled over to the side to let a car pass, came out of neutral again and it felt fine, gunned it in 2nd and 3rd with no problem.

 

Any ideas?

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go for it on the highway, see how it acts. my car has an intermitent and random ecu problem that causes the injectors to go wide open. I usually tap the ecu with my foot and its fine. Try taking off the kick panel covering the ecu, go for a drive, and if it acts up like you described, give the ecu a decent thump with your foot and see if it runs better.

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Didn't make it to the highway today. Was cutting out at second gear today, backfiring real bad from the exhaust, and now it is making a high pitch whining noise from the IM area. Just when I thought things were getting better. Lol.

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go for it on the highway, see how it acts. my car has an intermitent and random ecu problem that causes the injectors to go wide open. I usually tap the ecu with my foot and its fine. Try taking off the kick panel covering the ecu, go for a drive, and if it acts up like you described, give the ecu a decent thump with your foot and see if it runs better.

Old thread, but same thing seemed to work for me. Have had to tap ECU with my foot on a few occasions during a couple of months-so far gone the longest without any issues-about a month now. Even tapped it with foot on the gas to make sure that's what was seeming to fix it. Not sure if the issue lies in the plug connections, grounds, or the inner-workings of the ECU. Who cares for right now.

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Hooray for a new problem!!

 

Went to start her today, battery had water by the positive terminal, sapped her dry. Jumped the car, idle fine, but would choke out upon rev and the tach didn't work.

 

Let her warm up and she was fine. Let her run for a while, began to drop in RPMs, figured it was out of gas (it may will be, don't know honestly the sender is broken). Upon dying, the fuel pump decides it's going to steal all the battery's juice and continue to run or try to run after the car died. It was on a clicking frenzy. Hopefully my brand new 76 Fuel pump will fix that problem but I thought I would share.

 

Oh, also, after the car is off, a very slow slight tapping noise can be heard from inside the valve cover. Any ideas?

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The intake boot between the AFM and THROTTLE body

looks pretty sick.

 

If you have ANY air leak between those two points,

you WILL have problems, and may have misadjusted the AFM,

to compensate for a leak.

 

Positively no leaks allowed. :)

 

Just read the "not my car",

but still applies.

 

Also, take a spray bottle like windex with water,

and spray all the ignition wires, coil, and distributor

cap. ANY change in engine sound/running indicates a bad component.

Edited by jasper
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The intake boot between the AFM and THROTTLE body

looks pretty sick.

 

If you have ANY air leak between those two points,

you WILL have problems, and may have misadjusted the AFM,

to compensate for a leak.

 

Positively no leaks allowed. :)

 

Just read the "not my car",

but still applies.

 

Also, take a spray bottle like windex with water,

and spray all the ignition wires, coil, and distributor

cap. ANY change in engine sound/running indicates a bad component.

 

All that stuff is fine. Since you aren't too far from me Jasper, why not come down and give a guy a hand ;) Lol.

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Anyone want to come and get this thing running again I will pay them. I just spent an easy 3 hours trying to break the bolts to remove the old fuel pump... Couldn't break one of them. Rusted and stripped to hell Ready to set the car on fire. I would just bring it to my mechanic, but it doesn't start, the damn fuel pump just clicks, and angry loud clicks too.. It's mocking me I tell you!

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Update:

 

Car starts again. Found out that the alternator is not charging the battery, it is getting a draw from somewhere. Is there any common places I should look for the draw, I plan on getting a new alt anyway but just wondering where to look if anyone has any ideas.

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