Cutlass w/ LQ1 cold start missfire

[95LQ1VERT]

Hello all, new to the forum and I have a question to ask. Couldn't find it on the search.

 

I just bought a 1995 cutlass convertible with the 3.4 dohc, it has 135000 miles on it, and its in overall good shape. The previous owners had the transmission replaced along with a tune-up, water pump, thermostat, intake gaskets and such, but each morning since I've owned it i start it up and it miss-fires pretty bad and the idle fluctuates from 700-1700. Im just wondering what could be causing it to do that? When it warms up it runs great.

 

Thanks for any input!

[Schurkey]

Hello all, new to the forum and I have a question to ask. Couldn't find it on the search.

 

I just bought a 1995 cutlass convertible with the 3.4 dohc, it has 135000 miles on it, and its in overall good shape. The previous owners had the transmission replaced along with a tune-up, water pump, thermostat, intake gaskets and such, but each morning since I've owned it i start it up and it miss-fires pretty bad and the idle fluctuates from 700-1700. Im just wondering what could be causing it to do that? When it warms up it runs great.

 

Thanks for any input!

What does the scan tool show for coolant temperature during warm-up? How about desired/commanded idle speed?

[White93z34]

Pull a few spark plugs, make sure they actually changed them and that they are gapped withen spec. make sure to do it on a cold engine and use anti-sieze going back in. if you have a timing light check all 6 wires for spark with it.

[95LQ1VERT]

I will try and check the front banks plugs sometime tonight after work, and I will have to take it to autozone and run the codes. I believe the Previous owners removed the SES light because I personally have never seen it on... even before start up. And I took my Harbor frieght timing light back, because it barely worked.

 

**Also what is a good cheap spark plug that works decently well with this motor, I just don't see running $8 spark plugs. $5 max per plug haha

Edited September 25, 2012 by 95LQ1VERT

[Schurkey]

I will have to take it to autozone and run the codes.

Codes are fine. Get a REAL SCAN TOOL and start looking at the data stream.

 

I believe the Previous owners removed the SES light because I personally have never seen it on... even before start up.

That's going to screw things up.

 

And I took my Harbor frieght timing light back, because it barely worked.

Harbor Fright is pure junk.

 

 

**Also what is a good cheap spark plug that works decently well with this motor, I just don't see running $8 spark plugs. $5 max per plug haha

Look for non-Chinese Autolites (they're very scarce, since they've moved production off-shore years ago); or the ordinary (not Iridium or Platinum) AC. NGK is also well-regarded.

 

I'm not so afraid to run a Platinum/Iridium AC, as they'll last just about forever if the engine is kept in tune. I've got Iridium AC plugs--the ORIGINALS--in my 120K Trailblazer. Pulled them at 80K or 90K--I forget--and they looked so perfect I wiped anti-seize on the threads and screwed 'em right back in.

[95LQ1VERT]

What is a good scan tool? Isn't these cars a OBD 1.5?

 

Also when I checked the plugs they were Autolites made in usa, but they looked scorched. They had like a light colored coating on the prong that goes over the electrode, all the front three were like that. So they look to be out of the heat range and getting to hot?

[Schurkey]

What is a good scan tool? Isn't these cars a OBD 1.5?

Not a concern for a proper scan tool. I suggest buying a used PROFESSIONAL GRADE tool rather than the cheap-junk consumer grade crap for sale at Sears or Harbor Fright.

 

Also when I checked the plugs they were Autolites made in usa, but they looked scorched. They had like a light colored coating on the prong that goes over the electrode, all the front three were like that. So they look to be out of the heat range and getting to hot?

Photos would help a lot.

 

Very likely normal operation but with lots of miles on them. Fuel deposits build up on the electrodes. If the electrodes aren't worn round, they can probably be cleaned, re-gapped, coated with anti-seize, and re-installed. Most folks won't have access to a spark plug cleaner. I use a glass-bead blaster. A spark-plug-specific grit blaster is ~$20 and up on Amazon, most folks would rather just change plugs. If they have excessive wear, it's time for fresh plugs.

[runt]

Not a concern for a proper scan tool. I suggest buying a used PROFESSIONAL GRADE tool rather than the cheap-junk consumer grade crap for sale at Sears or Harbor Fright.

 

 

Even a GOOD used tool can be in the hundreds of dollars which is much more than most people care to spend on a tool that might get used a few times a year. Yes, I fully understand that you need good tools sometimes. Even a step further I can't see most people even being able to understand what is coming across that data stream.

[Schurkey]

Even a GOOD used tool can be in the hundreds of dollars which is much more than most people care to spend on a tool that might get used a few times a year. Yes, I fully understand that you need good tools sometimes. Even a step further I can't see most people even being able to understand what is coming across that data stream.

 

Used successfully ONE TIME, the ~$300--$400 used QUALITY tool has the potential to pay for itself versus hauling the car to a shop for diagnosis. Used successfuly TWICE and the tool is practically guaranteed to have paid for itself.

 

The point here is that I asked about coolant temperature sensor data, and the original poster says he'll "take it to Autozone and run the codes". You are clearly correct that there's a learning curve involved with automotive diagnosis.

[Galaxie500XL]

I have an ACTRON CP-9110. Works fine on my '95 "OBD 1.5" LQ1...

 

Got it for $50.00 on eBay.

 

What is a good scan tool? Isn't these cars a OBD 1.5?

 

Also when I checked the plugs they were Autolites made in usa, but they looked scorched. They had like a light colored coating on the prong that goes over the electrode, all the front three were like that. So they look to be out of the heat range and getting to hot?

[95LQ1VERT]

I will probably consider the Ebay scan tool.

 

Plus I stopped by autozone tonight and decided to pick up a new set of copper NGK V Power plugs, and some new plug wires.

 

Also just a little off topic, but is it normal for just 1 (driver-side) cooling fan on the radiator to kick on at about 210-215 degrees while in traffic? It seems to run hot while in stop and go traffic and I was think they should BOTH kick on at a lower temp and maybe stay on? Driving on the road it stay nice and cool.

 

Its a new car to me and I'm trying to work all the bugs out of it.

 

Thanks Everyone!

[Galaxie500XL]

Perfectly normal for the fan...the 2nd one does't come on till temps get above 235 IIRC...

 

I will probably consider the Ebay scan tool.

 

Plus I stopped by autozone tonight and decided to pick up a new set of copper NGK V Power plugs, and some new plug wires.

 

Also just a little off topic, but is it normal for just 1 (driver-side) cooling fan on the radiator to kick on at about 210-215 degrees while in traffic? It seems to run hot while in stop and go traffic and I was think they should BOTH kick on at a lower temp and maybe stay on? Driving on the road it stay nice and cool.

 

Its a new car to me and I'm trying to work all the bugs out of it.

 

Thanks Everyone!

[95LQ1VERT]

Thats some good reassurance, thanks Galaxie500XL . I will go about changing the plugs and wires when I get time . BTW I was reading your thread from a while back on how to change the rear spark plugs, could you tell me the way you ended up going on how to replace them?

[Galaxie500XL]

It wasn't too bad...just remove the strut brace, and pull the rubber seal at the back of the hood...a previous owner had cut small reliefs in the metal lip the rubber attaches to, to allow a long extension to sit straight over the plugs. The rubber seal will cover the reliefs when it's reinstalled-yours may already have been done by a previous owner, maybe not--remember to put a bit of paint on the cuts you make. A bit of a pain, but way better than pulling the plenum to change the plugs. NOTE...this won't work with the '96 and up LQ1...the plenum is a different shape, and covers more of the rear valve cover.

 

 

 

You may have read suggestions to "rotate" the engine for access, but the LQ1 uses a different engine mounting, and rotation isn't an option. Oh, yes, one more thing, if you're replacing the plug wires, the job is much simpler in routing if you remove the power steering pump. Easy to do...it's just 3 bolts behind the power steering pump pulley. The pump sort of "rolls" out, rotating the housing counterclockwise. It's a tight fit, but it WILL come out..be careful if you do this to suck out the power steering fluid, being careful not to get any spillage around the timing belt covers---power steering fluid isn't a good thing to get on the timing belt, and will quickly destroy it.

 

Be prepared for a shock...plug wires for the LQ1 are EXPENSIVE. I installed OEM wires, at the time, the cheapest I could find them was $150.00, but a few months ago rockauto.com was selling the sets for under $70.00

 

IMPORTANT NOTE: Don't move the car with the strut brace removed.

 

Thats some good reassurance, thanks Galaxie500XL . I will go about changing the plugs and wires when I get time . BTW I was reading your thread from a while back on how to change the rear spark plugs, could you tell me the way you ended up going on how to replace them?

Edited September 26, 2012 by Galaxie500XL

[95LQ1VERT]

That doesn't sound like to much of a challenge but I will give her a shot sometime. Also I might as well change the power steering pump while im at it because this thing sounds ridiculous with the squealing it does, good to know this info isn't it?! Thanks again

 

Also I know OEM is recomended but I like duralast, IMO they're priced great and work good. These were only $38.99!

[Galaxie500XL]

If you're planning to change the power steering pump, you're going to run into a problem...

 

'94 and '95 LQ1 Cutlass and Grand Prix used a variable orifice pump...RPO was NV7. you probably noticed a sensor plug in the top of the pump. The idea was to create a variable steering effort, based on speed, and steering wheel angle.

 

NO ONE carries that pump.

 

P/N for the pump is GM Part# 26047158, and for the actuator, GM Part# 26071775, but GM discontinued the pump and actuator years ago.. They're hard to find in junkyards...in 3 years, I've found 2.

 

NAPA told me if I would give them the old pump, they would have it rebuilt....for $250.00, and a 3-5 week turnaround.

 

Of course, you could always put a standard pump on the car, and leave that disconnected, but since it is controlled through the ABS computer, I've been reluctant to try.

 

BTW, if you DO use a regular pump, SAVE YOUR FLUID HOUSING. The housing is slightly different on the NV7 pump on your car, to clear the actuator...you don't want to lose that housing, if you ever found the proper pump, and wanted to switch back.

 

I did "frankenstein" a standard pump once, by swapping all the actuator components from my bad pump to the standard pump. Seemed to work well, but it's a couple hours of work to do so, and you MUST use your original fluid housing to make it work. A little later, I found a good NV7 pump in the junkyard, and put it on the car.

[95LQ1VERT]

Previous owners also claimed to of had the pump replaced a time before, however it sounds like it hasn't. I also checked for the "plug" you were speaking of, but i couldnt locate it. There is nothing on or around the pump that plugs into it beside the metal lines that transfers the fluid. A picture would help some.

[Galaxie500XL]

Here's a pic from my car of the NV7 pump..hope it helps!

 

[95LQ1VERT]

Hey I really appreciate that picture! However mine isn't the original so it shouldnt hurt to put in an autozone special hahaha! Btw I still havent got around to doing the tune-up, my work schedule is all whacky. But I will keep it updated.

[Galaxie500XL]

Good luck with it...at least you know what the plug looks like....I'm flying out to Alaska on Sunday, so I'll be offline for about 10 days, but keep everyone in the loop on what happens!

[95LQ1VERT]

I Finally got the time to do the plugs and wires on my Cutlass... I did remove the strut tower brace and removed the weather stripping but I didnt feel the need to cut the reliefs.

 

All the tools I used was a 3/8 ratchet, to a 3 inch extension, to a U-joint attachment and then to a 6 inch extension, ending on the spark plug socket. This method was effective and was decently quick.

 

But in the cold morning starts my car runs funny still, It revs up to 2,750-3,000 rpms and flucuates down to 600 rpms repeatedly for around 20-30 seconds. Could some parts need cleaned? throttle body, IAC valve?

[94 olds vert]

It wouldn't hurt to clean your throttle body and IAC. Also check your air filter if you haven't don't so in a while.

[95LQ1VERT]

I checked the filter and it was a "newer" paper filter, and I also looked at the throttle body and I noticed kind of a lot of carbon build up on the butterfly valve and the outside diameter of the butterfly valve. We'll see how it runs once i clean them tonight. Thanks!

[94 olds vert]

I've also had a lot of buildup on my throttle body on my 'vert before I cleaned it.

[95LQ1VERT]

I cleaned the IAC valve yesterday, and when I started it this morning it didnt rev up as high like it has been (only to a bout 2000 rpm but I think thats normal) , and the idle didnt keep dipping up and down. but it did stumble a little bit. I probably will have to clean it a little bit more to "perfect" it.