A new "my lt1 runs like poo" thread :p [Archive]

bottledbird68

10-18-2010, 01:16 AM

Ok, wound up driving the z an hour home in the pouring rain after work Thursday night. Car was running mint but now not so much. It started popping, sputtering, and backfiring randomly on the highway on my way home and now, even after the rain has stopped, is still doing it.
I did a quick look around at all the wires and everything looks ok but it feels like it's down a cylinder or two.
At first anything under 2500 rpm was horrible and almost undriveable. Now, it's cleared up a little, but still not so great under 2000 and downright horrible under 1500. It does however idle great and starts right up fine. It will pull all the way through to redline without too much drama but you can definitely tell it's just not all there. My other half said it best when she drove it, "the gas pedal feels like a spongy brake would react"
Not throwing any codes so could it still be the opti? It really feels just like a plug wire is shorting out but they look fine everywhere. Any ideas before I tear the front of the motor off, AGAIN!!!

My84Z

10-18-2010, 01:17 AM

opti or coil but you aren't alone not many lt1's have been running right lately :P

bottledbird68

10-18-2010, 01:22 AM

opti or coil but you aren't alone not many lt1's have been running right lately :P

Tell me about it. I'm getting ready to either do an ls swap, or eliminate the opti.
Been seriously considering opening up a hole at the back of the intake, dropping in a regular distributor, and just running a megasquirt.

Formula413

10-18-2010, 02:03 AM

Speaking as the owner of an LT1 that runs like a top, I can tell you that my car has zero issues driving in the rain, ever. Refresh my memory, is your opti vented? And you checked for simple stuff like vacuum leaks and fuel pressure? Connections on the coil are good? And there is definitely not a plug wire touching something hot?

bottledbird68

10-18-2010, 02:27 AM

Yes, opti is vented, none of the wires are touching anything hot, triple checked.
Didn't see any vacuum leaks, all of the ignition plugs look good.
Didn't check fuel pressure cause whatever caused it happened after it got wet the other night so I'm pretty sure it's ignition related. You can definitely smell unburned fuel from the exhaust.

I used to love lt1's. My old 9c1 caprice was awesome. I beat the daylights out of that car. Went through 3 transmissions and 2 rear ends but the motor was always strong and trouble free.
I don't want to hate lt1's but this one is making it hard not to. Grr...

Formula413

10-18-2010, 02:40 AM

Yeah I just realized fuel pressure issue wouldn't make sense. Is there any chance it could be a bad coolant temp sensor causing the computer to see a cold engine and dump fuel? If yours is the same as mine there are separate sensors for the gauge and the PCM so the gauge can read correct and the PCM can still be getting bad info.

I can't believe it's running that bad and not throwing codes. I'm just trying to come up with anything other than the opti that could cause it.

kaboom

10-18-2010, 10:30 AM

i have heard stories of the vented optis getting water in them and they start running just like that but i dont speak from experence.

frankzlt1

10-18-2010, 11:03 AM

i know you said no codes, could an o2 cause a problem.

KLAB

10-18-2010, 12:52 PM

Mine used to run beautiful. But I did an emissions delete and race headers with ory and now the air fuel ratio is all tweaked.. Still trying to track it down but Now its running good till about 3200rpm goes lean as you all saw on the dyno 17:1!!! WTF So, at least my ignition is good... knock on wood.

Formula413

10-18-2010, 04:21 PM

17:1 is leeeeean...

KLAB

10-18-2010, 05:09 PM

haha wow I meant lean I posted too early..

My84Z

10-18-2010, 05:49 PM

Kevin u can try cleaning the maf first 2nd would be an adjustable fpr to mess with it some

bottledbird68

10-18-2010, 11:51 PM

Didn't get the chance to tear into it today. Wound up taking a ride instead. However, today it's a little better. Now it's only breaking up under/around 1500 rpm. Not really backfiring anymore either.
But yeah, still no codes. It seems to be slowly clearing itself up but who knows if it'll go away completely and either way it would be nice to figure it out so I don't have to fear driving the car in the rain :p
Somene on ltxtech asked if my air filter got wet. I do have a cold air intake that has a cone filter down low in front of the tire. He said his does sometimes and screws up his maf. But, I'm not throwing any codes. I would imagine I'd have a code if it were O2's. I know my caprice did when the o2's went bad. So aggravating.

KLAB

10-19-2010, 01:14 AM

Kevin u can try cleaning the maf first 2nd would be an adjustable fpr to mess with it some

I'm gonna clean the injectors and maf and put a new fuel filter in. If that doesn't help aeromotive fuel pressure regulator time.

Formula413

10-19-2010, 01:22 AM

I dunno if a wet air filter could cause it or not, but since we're on that topic how big is the filter on your CAI? When I got my car it had a Moroso CAI on it, and it had a K&N cone filter on it that was so long it almost touched the splash panel. I replaced that with one that was a few inches shorter, which I found after some research was the same size as the one the kit came with. I just wanted a few inches of insurance in case I ever hit one of those sneaky puddles that looks 2" deep but it's 12" deep.

Batman

10-19-2010, 01:26 AM

Batman

10-19-2010, 01:27 AM

17:1 is leeeeean...
Scary lean......

bottledbird68

10-19-2010, 01:47 AM

bottledbird68

10-19-2010, 01:49 AM

as much as I hate to admit it (and I do) The LT1 is a great engine that is hampered by a unreliable ignition system. Chances are it is a coil or opti but I would do the LSX ignition upgrade way before I tried to do an LSX swap on an LT1 car.

Honestly, if I do get rid of the opti I'm leaning towards a conventional distributor and a megasquirt ecu. Probably cost less than half as much as the efi connections stuff. Unless I decide to try and work a deal with someone who may be selling their set up ;)

My84Z

10-19-2010, 02:42 AM

Honestly, if I do get rid of the opti I'm leaning towards a conventional distributor and a megasquirt ecu. Probably cost less than half as much as the efi connections stuff. Unless I decide to try and work a deal with someone who may be selling their set up ;)

Do you remember Rob's setup from new england dyno on the white 96ss?? That was a nice setup and very clean. He is still on Nems if you have ?'s I am sure he would answer them.

KLAB

10-19-2010, 03:08 AM

Yeah I'm sticking it out with the opti till it is declared toast. Then I will do the efi connections conversion. But no need to upgrade now :) Yep its pretty scary lean but only at the top end like over 3k rpm. Strange, but I've been driving it the past couple days and taking it off the road soon to straighten it all out.. :D :klab:

bottledbird68

10-19-2010, 03:30 AM

Do you remember Rob's setup from new england dyno on the white 96ss?? That was a nice setup and very clean. He is still on Nems if you have ?'s I am sure he would answer them.

Yeah I remember checking that car out years ago and it's the one that set me on this train of thought.
Doesn't seem like a huge deal. Just need a nice accurate distributor with a locked out advance so I can control timing with the ecu, then use the conventional cap to distribute the spark just like an old school small block.
Pretty sure you can get a megasquirt to control fuel and spark now. Iirc he used either a fast or a dfi set up. But at the cost of those I'd just go efi connection lol.

Only big issue I see is getting the hole through the intake in the right place for the distributor.

My84Z

10-19-2010, 03:33 AM

bottledbird68

10-19-2010, 03:41 AM

Yeah i think he used a fast but megasquirts are great for the money. I believe there is a template online there is also a place that does them online for the thirdgen people I can't remember the site but it's lt1intakes.com or something it's been awhile.

Yeah, that sounds about right. I knew there was a place online. If the opti is f'ed I'm pretty sure this is the route I'm gonna take.
It's also the route I think I'm gonna look into for my turd gen if I stick with the lt1 I have for it.

Formula413

10-19-2010, 03:42 AM

Oh, one other thing, since I'm supposed to be filling in for Pizza, I have to add...

He called the shit poo!!!

bottledbird68

10-19-2010, 03:43 AM

Oh, one other thing, since I'm supposed to be filling in for Pizza, I have to add...

He called the shit poo!!!

Calling it poo made me smile lol

ILuvPizzaTimes10

10-19-2010, 05:38 AM

If you go rear dizzy you have to drop the motor to remove it. I was going to go that route but after getting a lot og the ls1 stuff cheaper then off there site and really not liking how tight it is to work under the cowl anyway. I sed fuck that. And that's th e reason gm went with a front mounted opti in the first place. They actually have ltq blocks in some early 90's trucks but you can't telll unless you know what to look for because they ran a conventional dizzy setup. Anyway my point is either keep the opti and its issues. Or go efi and have tunability from a know and GREAT tuner. Megasquirt may be good for the price tag. But who will tune it? You'd be stuck tuning it yourself or paying someone more then a regular tune to do it for you. And that would negate the cost of the "cheaper" system as it were. I say check your lower opti vent hose the one soaked in oil and the one that probably fell off.

bottledbird68

10-19-2010, 01:47 PM

Trust me, I would have absolutely no issues with tuning it myself and honestly would rather. Tuned a number of carbe'd cars in my day with great success. Doing it with a laptop would be even easier.
Anyhow, if I stop being a pussy or it warms up a little this afternoon I plan to dig into it some today. :)

KLAB

10-19-2010, 08:39 PM

Anyhow, if I stop being a pussy or it warms up a little this afternoon I plan to dig into it some today. :)
hahaha!

bottledbird68

10-20-2010, 12:33 AM

hahaha!

What can I say, I'll call it like it is lol.

Anyhow, triple checked all the wires and connections. All was good. Also checked the lower vent hose, and while yes, it is covered in oil, it is still firmly in place lol.

Then I crawled under the nose and looked at the air filter. Tough to say if it's still wet but the mesh on it is definitely very rusty like it was soaked. So, I'll take it for a rip tomorrow and if it's still breaking up I'll try pulling the filter and see what happens :)

bottledbird68

10-21-2010, 08:36 AM

Ok, so, triple checked every wire connection and hose. Everything looks good.
Cars not throwing any codes whatsoever. Breaks up below 1,500 rpm, smooths out, and now when I wind it out wide open it stays fairly smooth until about 5,000 then starts breaking up again. But it's definitely down on power regardless. Feels like it lost a cylinder.
It also gets a weird burnt sweet smell to it when I wail on it.
Oh, and it's occasionnaly puffing some white smoke out the exhaust here and there, and, lastly, on a whim checked the radiator and it's about a third of the way empty.

Hmmmmm.......

Formula413

10-21-2010, 11:49 AM

Uh oh...how does the oil look?

ls6monte

10-21-2010, 04:21 PM

That doesn't sound/smell good Matt! :confused5:

bottledbird68

10-21-2010, 04:22 PM

Uh oh...how does the oil look?

Not bad....... Yet :(

If it wasn't such a bitch to do the plugs I'd compression test it.
I'm thinking fuck it, I'll run it for the next couple weeks until the snow flies before I tear into it and see what happens. Once it's apart and I know what's wrong I wont put it back together so I'd rather keep driving it for now. It's not overheating or anything yet. I figure worst I'll do is cost myself a couple o2 sensors.

If it does need to come apart I'm thinking a properly nitrous built 383 may be in order lol.

Batman

10-21-2010, 10:07 PM

I smell head gasket.......

bottledbird68

10-22-2010, 12:56 AM

I smell head gasket.......

Ahyup. That's what I'm starting to think. Yay :p

JoeyxGx2

11-01-2010, 04:33 PM

My car is misfiring at the top of second gear at close to redline ...

bottledbird68

07-18-2011, 08:58 PM

Ok, so, the problem went away for a while. And now I'm not smelling or losing anti freeze anymore and the fill cap/dipstick only show clean oil.

However, now the issue is back with a vengeance. Runs good until it gets up to temp then sputters, pops, loads up, backfires (quite spectacularly sometimes lol) and generally runs like a bag of smashed assholes.

So, I've recently replaced both o2 sensors, the iac, and pulled the air filter to make sure that wasn't the issue. When I changed the iac I pulled the throttle body off, removed the bottom plate, and cleaned it thoroughly.
Now, when it's cold it runs like a raped ape, better than ever. As soon as it gets up to temp it's just a mess. Falls all over itself and is almost undriveable.

HELP!!! I have someone just waiting for me to sort it out and I think I have the car sold for a good price. Want to get it resolved before he moves on but don't want to keep throwing parts at it...

Formula413

07-18-2011, 09:12 PM

I'm sure we've been through the obvious stuff like ECT sensor already, but Adam's car had a similar issue recently, and it was the wiring to the sensor (specifically the ground wire), not the sensor itself. And you must have tried the coil spacer mod already? But the symptoms are such a dead ringer for an ECT issue that I'd be surprised if that isn't somehow the problem. Not to mention the intermittent nature of the problem suggests wiring or ground.

bottledbird68

07-18-2011, 09:36 PM

Yeah I was thinking the same thing but autozone doesn't have the one that goes in the head. Only the one in the water pump. Which one is the ecu sensor? Isn't it the head one?
Last year when I had my ignition issues I went through every ground in the car, took them all off and scraped them all clean so I'm pretty confident it's not a ground unless it's in the harness.

And on another note, kid that wants the car just texted me and wants to meet up mid week... The way I feel right now I really think I'd rather have 6 grand in my pocket than the car lol.

Formula413

07-18-2011, 10:55 PM

No it's the one in the water pump that the computer reads. So you never replaced it? Even so it still seems like wiring or it would do it all the time. Do you have a scanner that can see ECT?

bottledbird68

07-19-2011, 02:54 AM

Yeah we have one of the expensive snap on scan tools here (modus I think?).
I swear it can read the last time I farted in the car.
Had it plugged in last weekend and it was reading 157 degrees if I remember correctly. But, I wonder which sensor it was getting that info from. Hmmm. I'll swap the ect in the water pump and see what happens.
I'm assuming it's not opti since it seems ok when it's cold.

Formula413

07-19-2011, 03:09 AM

Again it should be the sensor in the water pump, unless 95's are different but I don't believe that is the case. The best thing you could do would be to get the scanner on it while it's having this issue and see what it shows for ECT. Or warm up the engine and wiggle the wires to the sensor and see what the scanner shows.

I swear the biggest problem with optis is they cause people to mis-diagnose other problems because they are busy blaming the opti.

KB93z28

07-19-2011, 03:24 AM

The computer reads off the sensor in the water pump, and the sensor in the head is for the temp gauge in the cluster. I just replaced my sensor in the water pump not too long ago, you should be able to swap it out and only lose a tablespoon of coolant. Best way to get at it is underneath the car, and have the new sensor ready to go in as soon as you pull the old one out. Piece of cake.

bottledbird68

07-20-2011, 05:11 AM

Yup, changed the sensor in the water pump and it didn't change a damned thing.

Dammit. Kind of at a loss now. Thinking about trying another coil I have sitting here and hoping that helps...

ILuvPizzaTimes10

07-20-2011, 01:50 PM

Sensor is in the water pump its a 2 wire. The senderrr in the head is for the gauges. Its a 1 wire.

ILuvPizzaTimes10

07-20-2011, 01:51 PM

And hook it up to a damn scan tool so you knowwww what its doing and not guessing. Read data not codes!

bottledbird68

07-20-2011, 02:39 PM

And hook it up to a damn scan tool so you knowwww what its doing and not guessing. Read data not codes!

I did that a week and a half ago. It told me everything was fine.
Coolant temp was 157 degrees o2's were looking good. Not sure what else to look at or what they should be reading.

ZFreie

07-20-2011, 02:39 PM

And hook it up to a damn scan tool so you knowwww what its doing and not guessing. Read data not codes!Thats the first thing I do now when someones like my cars acting funny. I have a small hand held scanner that wasn't super expensive but gets the job done. to bad its a 95 and obd 1.5, he will need the correct cable. Uness he has a tech tool then nvm lol

monytorris

07-20-2011, 03:52 PM

It misses me....I can't believe that motor lasted this long in the first place!

bottledbird68

07-20-2011, 08:33 PM

It misses me....I can't believe that motor lasted this long in the first place!

Buy it back then lol!

bottledbird68

07-20-2011, 08:35 PM

Thats the first thing I do now when someones like my cars acting funny. I have a small hand held scanner that wasn't super expensive but gets the job done. to bad its a 95 and obd 1.5, he will need the correct cable. Uness he has a tech tool then nvm lol

Have the right equipment, been there, done that. As far as I can tell everything looks ok.
But, I'm also not 100% sure what everything should be reading.
Anyone have any links to the factory service manual for a 95? Or have one I can borrow?

ILuvPizzaTimes10

07-21-2011, 01:07 AM

ok so o2s should be swinging back and forth from around .150volts - ~850volts. in closed loop. you should have little to no knock retard on a rev/under a load. get a gauge on the fuel line that you can see from inside the car. i have one from advance thats a universal with a long enough hose i tape it to the wiper and go for a drive. ~45PSI and Never bellow 40. even up top Wide open. wen its hot and acting up get a spark gauge and see what the jump is right out of the coil and then what it is out of the opti. should a gap jump of almost .5" out of the coil and a SLIGHT drop out of the cap. about a .05 drop. and not for nothing but anytime ive seen a car do this after warming up its been a hot coil thats opened/gone up in resistance. or a bad regulator.

bottledbird68

07-21-2011, 06:04 PM

Ok, changed the coil and icm today. No change.

Plugged in the scan tool again, o2's are switching fine, coolant temp reads like it should, and it still breaks up and backfires.
It will rev freely with no load but as soon as I try and take it for a ride it's just getting worse and worse.
Don't really think it's a fuel pressure issue since it's blowing occasional black clouds lol.

I'm fucking lost and I need this fixed like last week... Grrrr......

Motaboata

07-21-2011, 06:14 PM

opti?

bottledbird68

07-21-2011, 06:21 PM

opti?

Only does it when warm, not cold. If it were the opti I would imagine it would be constant.
Plus it's an msd opti with maybe 20k miles on it, not some parts store or eBay junk

ILuvPizzaTimes10

07-21-2011, 06:42 PM

Check fuel pressure. If the pump is failing it will move less volume. The ecm will compensate for it with duty cycle on the injectors. And then wen the pump catches up it will puff balck like a mofo. Or its spark/cap related.

SLP IROC-Z

07-21-2011, 07:52 PM

plug wires? plugs? sounds like the car runs good in open loop but once in closed loop it runs like shit, so possibly sensor related. egr deleted on that thing?

bottledbird68

07-21-2011, 08:09 PM

plug wires? plugs? sounds like the car runs good in open loop but once in closed loop it runs like shit, so possibly sensor related. egr deleted on that thing?

Plugs and wires were new last year. All the wires were double checked and look good.
And yes, seems like when it goes into closed loop it runs like ass. Egr valve is still there but unplugging it makes no difference. Nor does it set a code so I'm assuming it was deleted in the tune along with the air pump and other emissions bs since unplugging all of that never set a code.

Need to sort it out before my buyer walks... :(

ILuvPizzaTimes10

07-21-2011, 08:16 PM

That's why she's upset. Your selling her!! Ahhh haaaa. Unplugg both o2's. Will keep it locked in open loop. And see if it still does it. This way you can determine if its heat soak or loop related.

SLP IROC-Z

07-21-2011, 08:43 PM

hmm, is the egr vaccum or electronic controlled?

jayws6

07-21-2011, 09:30 PM

Vacuum and solidnoid

jayws6

07-21-2011, 09:36 PM

I have mitcham5 on damand and access to my tech 2 GM with obd1 cable. But having. Time the weekend. Is all I have so call me hope we can work. Something. Out and l have fuel pressure. Gage.

ILuvPizzaTimes10

07-21-2011, 09:59 PM

And egr will run like poo at low rpm but up top will smootg out and it won't cause a backfire or a stumble under a load like he's describing. I could be wrong its happened before but I have diaged tons of stuck egrs and they always stumbled at idle like a cam and then up top smoothed out.