Question : LQ1 idling issue

[Nas Escobar]

Well, I have a 94 Cutlass with the LQ1 and since I've bought it, the car has always despised being cold started every day until spring came. Now it's the midway summer and the car is still doing the erratic idle that it would do when I would start it in the winter. I've had it cut off on me twice, but only when warming up. I suspect the MAF due to a strong smell of gas, but I'm not so sure. The smell goes away when the car is heated up and ready to run, and everything is fine with the car until the engine cools down to outside temp again. Then the cycle starts again. I've gotten the SES light on before, but it goes away before I can do anything to find out the info on it. Even so, I have not seen an ODB1 plug anywhere in this car so I wouldn't know how to diagnose it.

I guess my main points of questions are...

- Where is the ODB plug on the Cutlass?
- Where can I get a scan tool that can read these codes
- Can Auto Zone or anything of the sort help me in this or am I going to be spending good money on finding out why this car won't start normal.
- Is this the MAF or the TPS? or is there another sensor I should think about at this point?
- Is there any way I can figure this out without paying an incompetent "technician" that will only make me pay $200 to hear "derrrrr i dont kno" (yes, DC area techs are this bad.... especially on the VA side)

All help is appreciated.

[Purple pit]

I'd say you would have to take the lower dash cover off to find your ALDL plug(drivers side).

[Nas Escobar]

I'll check that out today.

I've been doing research on GM's ODB1 system... Is it true that jumping the "a" and "b" plugs with a paper clip will make the light blink the code that triggers the SES?

[pocket-rocket]

Yes. They are the last two to the right on the top row of the connector. The connector is bolted to the lower dash above your feet (well, more like about a third of the way towards your knees from your ankles) on the drivers side as purple pit mentioned.

Sent from my HTC One X using Tapatalk 2

[Nas Escobar]

Well, I checked this out 2 weeks ago, but I barely have time for forums nowadays.... the car still does the stupid weird idle whenever it's cold but I did find the ODB connector.

Now here's my problem... From what I've read around in forums, there's supposed to be 4 connectors, and the 2 on the top of the connectors are supposed to be jumped. Ok, cool no problem, but my car only has 3 plugs.

Here's a pic of it



So as we can see, there's only 3. I tried jumping the 2 in the corner and nothing happened. I also tried jumping the 2 on the bottom and same result.

Now, on this specific car (1994 Olds Cutlass Supreme), is there a specific way to get the light to blink, did the p.o. decide to screw around with the wiring, or is this car ODB1.5?

[Schurkey]

It may be time for you to buy a GM service manual.

Don't forget that rough cold idle is a hallmark of rotted lower intake manifold gaskets.

[Purple pit]

Use carb cleaner to check for leaks on the upper. Look at where the heads meet the lower intake and check for what looks like dirty water runs/ drips that have dried up. It is very common for the lower intake gasket to leak.

[Nas Escobar]

That is really NOT what I wanted to hear... But alas, I can't really fight this.

Now this is going to sound like a stupid question, but this is my first GM V6 (yup, the redhaired V6 is my introduction to the world of GM V6's) sooooo uhm... no easy way to say this, but where is the LIM gasket located on the engine? I know the piece of metal that covers the rear bank's valve cover (the same thing that people say you need to take off to get access to the spark plugs) is the Upper Intake Manifold, but where can I see my LIM?

Would spraying the carb cleaner near the LIM help me figure out whether or not it's the LIM, or is there no foolproof way to be sure that it's those gaskets??

I have been looking this matter up, and it seems some people experience coolant in their oil (or vice versa) and there is weird colors on the cap or in the coolant reservoir, both of which are not true in my case. I will recheck my coolant reservoir though to make sure.

I'm also more mechanically inclined than what it really seems right now, so if it really is the LIM failing, how hard is it to change them?

[walterdude]

One thing you have to remember, we're talking LQ1 here.... Some things are VERY different from the 3x00s... If a LIM gasket goes it won't get oil in the coolant or vice versa... The only coolant related thing is the short hose between the LIM and throttle body,, unlike the 3x00s where the LIM has coolant running through it and the gaskets are exposed to the oil... You need to take off the Upper intake mani to get to the lower... The upper mani is that metal thing you were talkin bout... Not too bad of a job really.. The gaskets seem to go fairly often... I did 2 on the original engine and it seems the new engine has that problem as well... For the life of me I can't find a leak, but there has got to be one somewhere... I'm going to try it with propane... Going to run a hose DEEP under the UIM and saturate that area...
I believe 94s were OBD1.5,,, so to speak... I think the way you'd have to get codes would be with an ALDL Cable and a laptop... Pretty sure you can't jump A-B and count flashes like with OBD1.. Professional scanners are VERY expensive..
I think I got to everything,,,,
GOOD LUCK,,,,
Tom....

[Schurkey]

Professional scanners are VERY expensive.

Not at all. A used Snap-On MT2500 with primary and troubleshooter cartridges good to '99 model year domestic (GM, Ford, Chrysler, Jeep) can be had for ~$300 on eBay, and will kick ass on any consumer-grade junk "code reader". I sold one--cartridge good to '99 domestics--for $270 on Craigslist about four or five months ago. The software is what drives the price--coverage of newer vehicles, or Domestic/Asian (or Domestic/Asian/European) will cost more.

There are other brands, and models of PROFESSIONAL-LEVEL scan tools, the prices are very reasonable if you don't need the thing to have software capable of VIN-specific communication with cars that are less than 10 years old. The prices climb considerably when the VIN-specific coverage gets newer than 10 years old; and a brand-new Snap-On Solus Ultra is closing on $4,000

[Schurkey]

I'm also more mechanically inclined than what it really seems right now, so if it really is the LIM failing, how hard is it to change them?

Not all that bad on my '92 and '93. Really, not bad at all. You'll lose some coolant from the quick-disconnect heater tube (common problem--the fitting for the tube screws into the engine, and is rotted internally. Replacement fittings are available through the Dorman Help line at any parts store for little money.) There's an O-ring sealing a coolant passage between the two big aluminum castings, but it's included in the gasket kit. There's a large, molded-rubber vacuum hose leading from the upper intake manifold to the brake booster that's is commonly deteriorated. Available from GM for not much money. You'll shatter some hard-plastic vacuum tubes--they get very brittle with age. Splice them back together with short sections of rubber vacuum hose from any parts store. Worst part of the whole deal may be removing the corrugated-steel tube from exhaust manifold to the EGR adapter. Not a lot of working clearance.

Once the upper intake manifold is off, the lower becomes pretty self-evident.

Be sure to clean the EGR passages while the whole mess is apart. They can plug with carbon. Same with the throttle body section of the upper intake manifold. Aerosol throttle body cleaner works wonders.

[caffeine]

You can buy an ALDL cable for pretty cheap and with free software you can do more with it than a scan tool

[Nas Escobar]

One thing you have to remember, we're talking LQ1 here.... Some things are VERY different from the 3x00s... If a LIM gasket goes it won't get oil in the coolant or vice versa... The only coolant related thing is the short hose between the LIM and throttle body,, unlike the 3x00s where the LIM has coolant running through it and the gaskets are exposed to the oil...

I should have known better... So in a nutshell.... driving this car like this; what am I risking here? How bad can the damage get if I keep ignoring it? Or better said, what can get damaged if I ignore the LIM gasket? Besides the car boggling and feeling like a cylinder isn't firing right at idle, the exhaust smells like gas. It kinda reminds me of those old school cars without the cat. Another thing that bothers me about the situation is that sometimes the car feels hesitant. As if it doesn't want to move. IDK if that's the trans limiting the engine (I know the trans in that car wasn't GM's best at the time to handle the power of the LQ1). Then there's 70MPH @ 3500RPM. Isn't that a bit ridiculous for this car with the top up?

I believe 94s were OBD1.5,,, so to speak... I think the way you'd have to get codes would be with an ALDL Cable and a laptop... Pretty sure you can't jump A-B and count flashes like with OBD1.. Professional scanners are VERY expensive..
I think I got to everything,,,,
GOOD LUCK,,,,
Tom....

From what the people on the W body forum are telling me, apparently, no W body came with 1.5. IIRC that mostly applied to the N bodies than the W ones. I may be wrong, but I'm just restating what most have told me about the W and ODB

[Schurkey]

what am I risking here? How bad can the damage get if I keep ignoring it? Or better said, what can get damaged if I ignore the LIM gasket? Besides the car boggling and feeling like a cylinder isn't firing right at idle, the exhaust smells like gas. It kinda reminds me of those old school cars without the cat. Another thing that bothers me about the situation is that sometimes the car feels hesitant. As if it doesn't want to move. IDK if that's the trans limiting the engine (I know the trans in that car wasn't GM's best at the time to handle the power of the LQ1).

1. Unfiltered air getting to the cylinders. Leads to cylinder wall wear.
2. Engine runs like shit. You need to get out-of-the-way of a crazy driver or unusual situation, you cannot rely on the vehicle to respond to your right foot. Could cause a collision when the vehicle hesitates instead of zooming.
3. Misfire of one or more cylinders leads to excess fuel getting to the catalytic converter. Converter overheats, becomes defective. Now you get to replace the converter, too.
4. Misfire of one or more cylinders leads to cold cylinder wall, and excess fuel washing the oil off the cylinder wall, leads to cylinder wall and ring wear, piston scuffing, and contaminated oil.
5. Reduced fuel economy and vastly increased tailpipe emissions.
6. Additional wear of motor/transmission mounts, and the rubber of the torsional damper due to excessive engine vibration
7. Reduced pride-of-ownership knowing there's a real fault with the vehicle that you have to try to ignore.

Then there's 70MPH @ 3500RPM. Isn't that a bit ridiculous for this car with the top up?

So you've got trans problems, too. Failure to engage fourth gear (overdrive) and/or failure to engage the torque converter clutch. Steady 70 mph should be about 2100 rpm more-or-less. The early intake manifolds had a resonance point at about 2200 rpm, the engine will "hum" like it's happy. That happens about 73 indicated mph on my '93, and about 75 indicated mph on the '92, I suppose minor speedo calibration or tire-diameter differences account for the slight difference in indicated mph.

From what the people on the W body forum are telling me, apparently, no W body came with 1.5. IIRC that mostly applied to the N bodies than the W ones. I may be wrong, but I'm just restating what most have told me about the W and ODB

"OBD 1.5" is a TOTAL NON-ISSUE if you have a REAL scan tool. You'd never know there was such a thing as OBD 1.5, except shitty consumer-grade code readers and scan tools aren't sophisticated enough to work properly.

[Purple pit]

Sorry Nas, I was thinking about the newer 60 degrees. Disregard my last post.