No miss with EST disconnected-FIXED!
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Car: 1987 Trans am
Engine: 350 Vortec Stealth Ram
Transmission: T-5
Axle/Gears: 02 SS Torsen Zexel 3.42
No miss with EST disconnected (2 years later, new engine, still have a miss)
Trying to track down a intermittent miss at idle I've had for a few months. A little history on the car. It's a 1987 Trans Am with the 5.7 TPI engine. I've replaced the coil, plugs and wires, new distributor from Autozone. Bosch 3 injectors. Nothing seems to remedy this miss unless I unplug the EST. When I do that it's smooth as day. With it plugged in I get a intermittent miss cold or hot and at idle and very low throttle. Also get the popping through the exhaust on deceleration. I don't have any SES codes either.
Last edited by L98GTA87; 09-14-2015 at 08:33 PM. Reason: Still need help with problem
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Car: '86 Bird, 96 ImpalaSS, 98 C1500XCab
Engine: LG4, LT1, L31
Transmission: 700R4, 4L60E, 4L60E
Axle/Gears: 3.73 Tors, 4.88 spool, 3.73 Eaton
Re: No miss with EST disconnected
I had those exact symptoms on an 1986 LG4. Fixed with an ECM swap.
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Car: 1987 Trans am
Engine: 350 Vortec Stealth Ram
Transmission: T-5
Axle/Gears: 02 SS Torsen Zexel 3.42
Re: No miss with EST disconnected
Funny you mention that because The EGR hasn't been working and has been capped for as long as I can remember but it's not throwing any codes for it. Same for the EGR solenoid. It'll easy throw a code for the EST or MAF.
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Car: 1987 Trans am
Engine: 350 Vortec Stealth Ram
Transmission: T-5
Axle/Gears: 02 SS Torsen Zexel 3.42
Re: No miss with EST disconnected
I ordered a ALDL cable to start some data logging. Will search the JY for some ECMs. According to this page provided by this site https://www.thirdgen.org/ecminterchange, any of these ECMs will work i'd just have to use my PROM? I have the 165 ECM
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Car: '91 GTA, '92 T/A Convertible
Engine: GTA: 350 w/Vortec heads, T/A: 305
Transmission: Pro-built 700R4
Axle/Gears: GTA: 3.27, T/A: 2.73
Re: No miss with EST disconnected
For a quality ECM that you know would work, I would highly recommend hitting up TunedPerformance on this site. I got a replacement one from him for $50 and I know it would work.
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Car: 1987 Trans am
Engine: 350 Vortec Stealth Ram
Transmission: T-5
Axle/Gears: 02 SS Torsen Zexel 3.42
Re: No miss with EST disconnected
I uploaded a video so you guys could get a better idea of the miss. I drove around with the EST unplugged for a few days taking it easy. Plugged it back in tonight. Another key issue I've been having is bad pinging at WOT. Have tried different grades of gas from different shades of gas stations. Didn't help a thing.
http://www.youtube.com/watch?v=0_WDk...ature=youtu.be
http://www.youtube.com/watch?v=0_WDk...ature=youtu.be
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Car: 1987 Trans am
Engine: 350 Vortec Stealth Ram
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Axle/Gears: 02 SS Torsen Zexel 3.42
Re: No miss with EST disconnected
I played with the timing with the EST connected and the miss is nearly gone. Nothing like what it was.
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Car: 1987 Trans am
Engine: 350 Vortec Stealth Ram
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Axle/Gears: 02 SS Torsen Zexel 3.42
Re: No miss with EST disconnected
Tried a different ECM and ESC. Still the same problem with EST connected. Only thing I haven't done at this point is the knock sensor. Any suggestions here?
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Car: 1987 Trans am
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Re: No miss with EST disconnected-UPDATE
Unplugged the knock sensor and still same thing. Nobody has any pointers for me at all?
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Car: 1987 Trans am
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Re: No miss with EST disconnected-UPDATE
Checked all grounds and were good.
#13
Re: No miss with EST disconnected-UPDATE
Put #1 up on TDC compression stroke & then check the mark, I know its hard on a sbc, I use a piece of a coat hanger & feel the piston as it comes up.
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Car: 1987 Trans am
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Re: No miss with EST disconnected-UPDATE
I did this earlier today. Used some single automotive wire. Had my fiance put her finger over the hole until she felt air and I heard it as well. Rotor was pointing dead at number 1 cylinder, but the timing mark on the balancer was at the 9 o'clock position.
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Car: 1987 Trans am
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Re: No miss with EST disconnected-FIXED!
Just wanted to update you guys on this. My balancer had in fact slipped nearly 180 degrees from the keyway. Not only that, it slid back towards the timing cover. So replaced that. But my main issue with the EST was the distributor. Bought it about 12 days ago from AutoZone so go figure. I appreciate all the help. This is a awesome community.
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Car: 1987 Trans am
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Re: No miss with EST disconnected
This miss came back not long after but chalked it up to something in the engine.
2 years and a new engine, it's still there! Without making this long I have a video of how it is now and a short list of what I've done since swapping a new engine in a few weeks ago.
Fuel filter
Injectors
Another brand new distributor
Swapped ECM and PROM
Replaced MAF
O2 sensor
Swapped ign coil for known working one
Here's video
2 years and a new engine, it's still there! Without making this long I have a video of how it is now and a short list of what I've done since swapping a new engine in a few weeks ago.
Fuel filter
Injectors
Another brand new distributor
Swapped ECM and PROM
Replaced MAF
O2 sensor
Swapped ign coil for known working one
Here's video
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Car: 88 Chimera
Engine: 1994 LO5 5.7L
Transmission: 700R4
Axle/Gears: 2.73...?
Re: No miss with EST disconnected-FIXED!
Whats common between the 2 engines?
I.e what else did you reuse with relation to ignition?
I.e what else did you reuse with relation to ignition?
#21
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Re: No miss with EST disconnected-FIXED!
I guess it's worth mentioning I put in a brand new complete distributor yesterday, the miss was still there but it wasn't as profound like in the video.
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Re: No miss with EST disconnected-FIXED!
Is the miss limited to 1 cyl?
I.e if you short cables to ground 1 at a time, can you find one where the miss nothing changes?
If you short a 'good' cyl, you'll know.
I.e if you short cables to ground 1 at a time, can you find one where the miss nothing changes?
If you short a 'good' cyl, you'll know.
#23
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Car: 1987 Trans am
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Axle/Gears: 02 SS Torsen Zexel 3.42
Re: No miss with EST disconnected-FIXED!
Isolated that as well. With a timing light anyway, went around all the wires. They all produced the same light pattern.
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