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1G 4G63 non turbo with bad miss at 3200-4000 rpm

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zkheasley

Proven Member
70
13
Jan 25, 2014
marietta, Ohio
I have a 91 eclipse and since the day I bought the car its always had a miss. I've searched every forum on here and can't find anything for this. The motor cuts out like its hitting the rev limiter at 3200 rpm's and around 4000 it takes off and runs perfect. I used this car strictly for racing so I usually can keep the rpm's up there with no issues but restarts sure suck. Parts I've changed so far that didn't help are coil packs, ignition module, plugs and wires, cams, ecu, tps, maf, head and gasket, intake gasket, injectors,fuel rail, fuel pump, fuel pressure regulator. If you know of a post that may help me out or have any advise I wanna here it.
 
I have a bad oxygen sensor cause a similar problem on a couple dodge vehicles, might be worth a try.
 
Would like to know a solution to this problem as well. Having very similar issue with a non-DSM, except seems like when engine is under load it runs much better so thinking it might be timing-related.
 
Spark plugs gapped at .044' where a lot of 4G63 NT users think that the plugs needs the turbo gap of .028 ?

A weak or bad Coolant temp sensor can cause the hard hot starts..

Sounds like a fuel delivery issue where the pressure drops to the injectors at a certain RPM. Checked rail pressure per chance?
 
Hey guys, OK so I've dbl checked the plug gap and it was set at .45 and I made one of those handy cut down bolts for a fuel pressure check which turned out to be around 35 psi which is pretty close to what the DSM bible says it should be.As far as restarts goes what I meant was during a race if we have a caution I have to over rev in 1st gear to clear the dead spot in 2nd. I've never had any problems with the car actually starting, sry for the confusion. This miss has totally baffeled me!

Also I forgot to mention I switched out the cas with another used one at the track once but it did nothing different, still had the dead spot from 3200-4000
 
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I am having a similar issue with my 2g tsi. Mostly if I'm cruising at Highway speed. It smells like I'm running super rich, I have yet to hook my aem uego wide band up. Mostly cause I've heard varying reviews so I'm doing more research before i commit to it. If I hammer down and go wot it seems to be fine. I've replaced coil packs, plugs, wires, coil pack power transitor. So I'm wondering if it's more likely to be a bad o2 sensor or a bad cas.... If anybody has had this issue and can shed some light I'd appreciate it.
 
I've had the car for a year and I haven't replaced it. Though my engine temp gauge seems to work fine.
 
Did you inspect the main wire harness for any cracked or burned wires? also look for damaged wire connectors/pins etc.

if you really have the time, you could pull the whole main harness out and get an ohm meter, and test that all the engine connectors are getting to the ecu.

I had similar issues on my 1g tsi, it turned out to be my power transistor wire connector was damaged.
 
I've had the car for a year and I haven't replaced it. Though my engine temp gauge seems to work fine.

There are two different coolant temp sensors, one for your gauge and the important one for your ecu, the ecu sensor is a two wire sensor and is vital to your car running right, any coolant temp sensor thats more than a couple years old should be replaced.
 
Thanks I will definitely check these things and get back to you guys with an update. I appreciate all of you taking the time to help me out! Where is the one for the ecu stashed motomattx?

So please tell me if this sounds way stupid, today I hooked up a 3" gm maf and translator after bov and my problem is gone.... Could it have simply been that the bov was originally not recirculated like it should have been? One of my friends mentioned this could've been the issue and it kind of makes sense to a point. Just curious what the rest of you think on this.
 
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Thanks I will definitely check these things and get back to you guys with an update. I appreciate all of you taking the time to help me out! Where is the one for the ecu stashed motomattx?

So please tell me if this sounds way stupid, today I hooked up a 3" gm maf and translator after bov and my problem is gone.... Could it have simply been that the bov was originally not recirculated like it should have been? One of my friends mentioned this could've been the issue and it kind of makes sense to a point. Just curious what the rest of you think on this.

At the bottom of the thermostat housing.
 
Wide band will be going in today, been a busy morning but I'm gonna head out and get it going in a few minutes.
 
+1 on coolant temperature sensor.

As Mottomattx stated there is more than 1 sensor in the thermostat housing. There's one that goes to the gauge cluster, one for the ECU, and one for EGR.. (seems like there's actually another one but I can't remember at the moment).

The reason I suspect this is because of rough start ups.
 
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2G Enthusiast.... I'm assuming you cut into the original maf wiring harness, is it possible you may have had a bad wire going to the old one or even a bad maf? I've switched mine out with no great outcome but never thought to trace the wires. I still haven't figured this thing out and I'm beginning to think its a lost cause.
 
Didn't have to cut into the harness. I used the maf translator. Got my wide band hooked up and I'm running great now. I honestly think I was just hitting fuel cut due to running to rich. Only thing I can guess is because the previous owner didn't recirculate the bov. Instead just dumped it into the atmosphere. Sorry it took me a couple days. Had alot going on. The only wire I had to splice into was on the cas. And now come to think of it i did fix the wires on that when I spliced in they looked a little frayed on the plug end so I pulled the pins and cleaned them up some. How does the plug on yours look? And where are you located? I have a complete 1g wiring harness if you think you may have a wiring issue.

And I still have not a clue which coolant temp sensor goes to where! Lmfao. I have two in the thermostat housing. One large one really small.
 
Didn't have to cut into the harness. I used the maf translator. Got my wide band hooked up and I'm running great now. I honestly think I was just hitting fuel cut due to running to rich. Only thing I can guess is because the previous owner didn't recirculate the bov. Instead just dumped it into the atmosphere. Sorry it took me a couple days. Had alot going on. The only wire I had to splice into was on the cas. And now come to think of it i did fix the wires on that when I spliced in they looked a little frayed on the plug end so I pulled the pins and cleaned them up some. How does the plug on yours look? And where are you located? I have a complete 1g wiring harness if you think you may have a wiring issue.

And I still have not a clue which coolant temp sensor goes to where! Lmfao. I have two in the thermostat housing. One large one really small.

Of course you cant dump to atmosphere without speed density tune, even with wideband its not a good idea.
 
I'm in Ohio but if you have a 1g turbo fwd harness I'd be interested,,, I may be the only fool on here that's about to try DSM link on a non turbo!!
 
98 - gs that picture helped a ton! Thanks!

And yes I do have a complete 1g fwd harness just have to move some things around in my shed full of dsm parts. It's getting pretty full these days and could use some cleaning out anyhow. Let me find it and talk to one of my buddies at ups to figure out what shipping would be.
 
Extremely sorry man. I recently started a new job and haven't had much time for anything other than work. But I haven't forgotten.
 
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