2.8L Freezing me out!

[Pushrod_V6]

Long time lurker, first time poster....... :D Here's the stats on my sled:

1989 Celebrity Station Wagon / Fleet Car; 121,000 / 2.8L V6 - currently running without a thermostat (this detail important).

Bought the car a month ago, threw a new radiator in it & redid all the brakes. Now, the car runs outstanding, I mean perfect until the coolant temp gets over 170 degrees. Because of the lack of a thermostat (removed by the prior owers mechanic) and the cold weather here in PA, it only gets that warm once I'm in stop and go traffic.

Once the temp gets over 170, BAM, like someone hit a light switch, the car runs like absolute a$$. Missing, hestiting off the line, inability to control idle speed (normally too low), stalling, etc. Once in motion (if it hasn't stalled by this point) it runs fine. Also, once the temp drops back below 170, viola! Runs perfect at idle. Lastly, and this may help the diagnose, if I park the car when it is warm, and go to restart it the car starts immediately, the idle will stumble, the revs will shoot up to over 2k, and then creep back down to a normal idle. If the car is cold, it starts and idles normally.

I realize that the car is entering "closed loop" once the temp is over 170, resulting in the fuel maps changing. I cannot find a vacuum leak anywhere on the car (I realize that means there isn't a leak, I just didn't find it). The exhaust is new from the engine back - including converter - and I don't want to start throwing parts at this thing.

There is no check engine light and no stored codes, and the ECM checks out OK. I am leaning towards a failing Idle Air Control Valve, but I am looking for other options.

Thanks for reading and any help you can provide.

Pic for Clicks:

[dcjredline]

Well IAC has nothing to do with temperature so I would think thats not it. You should get a service manual and test EVERYTHING you can. Look at the Coolant temp sensor and make sure what the computer is seeing is whats actually going on.

I found out once that the computer in my 90 6000 wasnt getting normal readings from the 02 sensor but when I actually tested the 02 with a meter it was doing what it was supposed to. Checked the wires and figured out the computer was HOSED.

SO just cause the computer "sees" a bad sensor DONT assume it is bad. Half of the sensors in that car can be brought to AutoZone and bench tested.

No one on here will be able to give you a deffinate answer to whats wrong, all you will do is replace parts on suggestions from what it sounds like. With out testing you cant get an accurate answer.

KEEP US INFORMED.

[Pushrod_V6]

Well IAC has nothing to do with temperature so I would think thats not it.


I realize the IAC has nothing directly to do with temp, but doesn't the input and response of the IAC change as a result of temperature? And I know that I am not going to get a definitive answer, I'm just scratching my head as it is only occurring once the car is fully warmed up.

It plays like a vacuum leak, I just sure as hell can't find one. :mad:

Regardless, thanks for the prompt response. I'll keep y'all in the loop.

[Pushrod_V6]

Oh, and the freezing meet out reference in the title..... it's been in the 20s here the past couple of days.... and the car w/o a thermostat doesn't really throw out a lot of heat. :eek:

I just don't want throw a thermostat in this sled until I can get it to run right when its warm.

[LordDurock]

Oh, and the freezing meet out reference in the title..... it's been in the 20s here the past couple of days.... and the car w/o a thermostat doesn't really throw out a lot of heat. :eek:

I just don't want throw a thermostat in this sled until I can get it to run right when its warm.

okay.............a trem is like 7 mints of work and 10 bucks. do it might help.

[dcjredline]

Durok the therm is just going to make his problem worse. As of now it doesnt get to closed loop mode if he puts one in it it will be in closed loop alot more.

[LordDurock]

true.............. um check the wiring.......... check the computer it might be getting to hot...........just a crazy guess

[Pushrod_V6]

true.............. um check the wiring.......... check the computer it might be getting to hot...........just a crazy guess

All I know is some subsystem, once the car gets into closed loop (170+), is f*ing up and causing the car to run like tuchas. Believe me, I want the thermostat in there now that it is so damn cold out.

The old owner's mechanic figured the easy "work-around" was to take out the thermo instead of dealing with it. :rolleyes:

[Slacker]

My car does the same thing. (Same engine, just it's carbed) Well, it doesn't stumble once the car is going but will idle poorly at start, especially after it was completely warmed up.

I'm thinking, as said before, either a sensor is on it's way out or the computer isn't getting the right values.

My car doesn't seem to have any vacuum leaks that I know of either. :\

[LordDurock]

All I know is some subsystem, once the car gets into closed loop (170+), is f*ing up and causing the car to run like tuchas. Believe me, I want the thermostat in there now that it is so damn cold out.

The old owner's mechanic figured the easy "work-around" was to take out the thermo instead of dealing with it. :rolleyes:

i come from 6.5 land and the ip pump drivers when they fail do the samethings when they get hot....................it worth checking out the computer. or a lose wire or something

[Tonglebeak]

Just my 2 cents, closed loop occurs@130 degrees according to my service manual.

[mickstan_VR]

O2 sensor. Coolant temp sensor at the waterneck. EGR valve possibly.

[86euro]

I agree, coolant temp sensor, maybe O2.

[85_Ciera_Rebuild]

until the coolant temp gets over 170 degrees



How did you determine this (170 degrees)?

Did you attempt to change out the Computer's temp sending unit? Not the idiot temp sending unit.

Do you have, or know someone who has a Tech Reader?

Thermostat - Not good, BAD, to leave it....OUT

[dcjredline]

Easy you guys, I think its safe to ASS U ME that he was just guessing on the temp that it acts funny on. He is basically just saying when the car gets warm.

[CieraSL92]

I would remove the IAC and clean it, and spray the inside of the TB with TB cleaner to start with.

Mine would do what you describe when it had bad plug wires, run okay till closed loop, then hesitation and missing up near 5000RPMs Didn't stall though..

The coolant temperature sensor/O2 should be removed and taken to a parts store, or mechanic of your choice to be tested. Ideally a scantool, but there hard to come by.

Let the car sit overnight, with the climate control lever in the off position-in the morning before starting it, slide it over to vent. you should hear it hiss, indicating that the vacuum ball has a reserve and there are no leaks.

Beyond that, a tune-up is in order.

[dcjredline]

good trick about vacuum

[Pushrod_V6]

Thanks for the feedback guys, appreciate it. As far as the temp goes, I was going off of the word of another tech about the changeover temp from open to close loop - thanks for the correction Tongle.

Ciera, I saw your suggestion about the vacuum trick on another thread here a while back and I tried that, I definitely get hissing from the system in the morning. I still checked for leaks though - a tune up is going to have to be in this car's future. I don't get any missing though once the car comes off of idle, and the wires are fairly new (definitely not original). The prior owner, who was in his late 80's dumped a ton of money at this car before giving up on this issue and the radiator (that I swapped in his driveway B4 driving the car home) leading me to think this is just something stupid. Most of my automotive background is either carbs or OBDII so seeing the car run this poorly in closed loop @ idle w.o a stored code makes my head spin.

85_Ciera, I know it is bad for the system to leave the thermostat out - I am going to put it in and just crank the idle speed up to 3500 to keep it running. :D (Yes, I am kidding about the idle - sort of).

Wellup, once the weather clears a bit here I'll get the wife's Cooper out of the garage and start troubleshooting this sled. I'll keep ya posted.

[Pontiac6ksteawd]

To me it sounds if the EGR is having issues.Try taking off the vacume line to your EGR valve, and plug it. Then start your car and let it warm up, all the way up, to where you would normally see your problem. And see if it is still there..

Cleaning your IAC is also a very good sugestion, the EGR gases go right thru there, and it gums up really easily. My cars EGR just went wacky too, but mine thru a SES light for it.

EDIT: I just noticed your tool box, I have the same exact unit. Love those craftsman tool.

[dcjredline]

Well the computer sometimes doesnt set a code for itself being messed up. Keep that in mind.

[85_Ciera_Rebuild]

1989 Celebrity Station Wagon...2.8L V6....inability to control idle speed....revs will shoot up to over 2k, and then creep back down to a normal idle.

If there is a vacuum leak (or messed up IAC valve)...the computer will have to go "hunting" for idle. On FWD vehicle, there is a PVC valve on firewall side of engine's valve cover...check it out with mechanic's mirror.

Before motor is warmed up, the engine is using a default map, but once in Closed mode, those parameters like O2/Map/TPS are being used...a much leaner fuel burn, and if there is a vacuum leak, guess what?

Do a vacuum check (tee in a vacuum gauge)...and watch it while driving...

[85_Ciera_Rebuild]

Try taking off the vacume line to your EGR valve, and plug it.


I think on that motor, you can just press bottom side of EGR at idle...if engine starts running rough, then you know EGR is still seating tight.

It may be a pill to plug EGR line...

[Jr's3800]

Ok... Being that this is an 89 2.8 i will take a guess and say it had the Digital EGR Valve? If this is the case it is possible for it to be sticking... Its functionality is Dependant on engine load and temps iirc... May be worth a check and or cleaning..

The IAC is also another that may need to be cleaned.. it will be worth the time to go ahead and clean it as preventative care..

Its hard to say what the issues is going to be... I agree with the possibilities listed..

O2 sensor
ECT Sensor
Possible unhappy ECM..

And at the same time what kind of Plugs are in the car? The GM DIS system can get a little picky about Plugs..

Any idea if the car has the Original O2 sensor or a Bosch Replacement... Original O2 will be a skinny body( size of a spark plug ) a bosch replacement will be a Fat Body almost like a roll of Quarters..

My best offer of advice is to toss a scan tool at the car... If you know anyone with an Actron CP9110 with the GM card and ALDL cable you will be able to read your car with it... the actron CP9145 with the ALDL cable or the 9150 among several others will read the 89 Celebrity..

The tool will give you the live data and may help point you in the right direction..

[Pontiac6ksteawd]

89's are still vacume, as all 2.8's are vacume. Its the advant of the 3.1 that the digital EGR came out, with a few exceptions. The 3.1 in the AWD is vacume, and the 3.1 in the TGP's are vacume as well.

[85_Ciera_Rebuild]

dumped a ton of money at this car


Any hints...what parts were replaced?


just crank the idle speed up to 3500 to keep it running. (Yes, I am kidding about the idle - sort of).


The Computer Controls Idle...do not mess with any adjustments....in turn, it is affected via if AC is on, battery voltage, etc.

1. Ether - In open air with engine idling, spray it around motor gently, underneath intake manifold, backside of motor where PCV valve is located, around all vacuum lines, etc.

[85_Ciera_Rebuild]

O2 sensor Bosch Replacement..
...My best offer of advice is to toss a scan tool at the car...


Until we know what parts have been thrown at it, we are just spinning our wheels...

We don't even know if this vehicle has Speed Density Update, or was corrected by then.

A scan tool will assist greatly, but if a Speed Density Update was done, then specific readings are meaningless....

I wonder how he checked the Code...I can't recall if he stated if he used a Code reader, and what Code Number he got...you do get one number...

[Jr's3800]

According to the Schematics for this car there is No MAF

[mickstan_VR]

Correct. '89s did not have the MAF. IAT was in the canister.

[Pushrod_V6]

I wonder how he checked the Code...I can't recall if he stated if he used a Code reader, and what Code Number he got...you do get one number...

The old paperclip technique...... nothing fancy. I got the code 12 (or maybe 13 - too many nights up late working on the house). I really appreciate the feedback here, thanks again guys. I hope to get an opportunity for a teardown after work Saturday (again, once I get the garage back from my wifey...)

As far as $$$$ thrown at the car, there's a new exhaust - manifold back - including cat and O2, new front brakes (rotors, pads, calipers!) I mean, if I took all the receipts from the year 2000 and stacked one on top of the other it'd be almost 1/2 inch thick. In that time he drove it 18k.

As far as heat, it is cold as balls here. So I just took the upper rad mount off last night and cut a thick piece of cardboard to block the radiator. Today, it was considerably warmer in the car. :D I plan to put in a thermostat in Saturday too and get the cardboard out.... I know the cooling fan works, and it still didn't come on in traffic today so I'm thinking that I'm good from overheating until Saturday.

I'm hoping to talk with the old owner tomorrow to confirm with him the thermostat was removed to prevent the car from warming up, and not from overheating due to the original rad (that had a completely bad core.) That could be the cause of its poor running in closed loop to begin with - who knows. But it does make it interesting.

And seriously, thank you again to for the suggestions.

[85_Ciera_Rebuild]

According to the Schematics for this car there is No MAF

Thanks...then apparently, they had a serious problem then with 2.8s using MAF in 88 era; an VoTech instructor indicated something like 80% failure rate then on MAF sensors.

[85_Ciera_Rebuild]

...code 12...put in a thermostat...

If you can't find a Scanner tool to use...try to find/buy the computer's temp-sender unit.

I have not looked at mine, but the computer's temp-sender may have been used on a long list of GM Vehicles...all the way up to 2007, on some.

If your Temp-Sender unit is giving false details, the computer program is not "adaptive," so stuff will happen.

Mine is acting up, but I have not borrowed a scanner tool yet...I think TPS voltage and/or Temp Sensor is messed up, only when vehicle is started after it has been warmed up completely does it have a problem with idling...computer is off sync on something.

Most are computers work this way, garbage in, garbage out...and if temp/TPS is flucating, guess what happens...fuel/air is off.

Btw, you do have multi-point...or TBI??? I assume you have checked fuel pressure?

[CieraSL92]

89 2.8 Was multi-point.

[85_Ciera_Rebuild]

...talk with the old owner tomorrow to confirm with him the thermostat was removed to prevent the car from warming up...

Saturday Schedule: $27.00 Investment

1. Install New 195 degree thermostat
2. Install New Coolant-Temp-Sender for Computer


Sunday Schedule:

1. Go Cruzen....

My 88 Beretta has digital dash, but I checked actual temperature at thermostat housing area (where thermostat and Temp Sender is located) with MasterCool Infrared Thermometer, (http://www.autorepairmanuals.biz/site/573683/product/MTC52224ASP) and found temp readings around 195 degree range....but my in dash guage shows a lower reading than normal (about 3 bars lower).

It's too cold outside to mess with this, but there is only one temp sending unit (that I have found), which is located below thermostat housing....sometime next week, I will install another temp sender unit ($15.00), and my hunch is the digital guage will increase by three bars, and that warm starts will be more smooth...of course, if I had a tech scanner, I would know if temp sender is bad, or digital dash guage is bad...since I used an Infared Thermometer to confirm actual temp that temp-sender is seeing (about 195-200).

Hence, if a person does not have a tech scanner, there sometimes are ways to figure it out...but not always....

In any event, if you install the thermostat, install a new coolant-temp-sender...and check to make sure the Engine's ground wires are cleaned up...your buggy may be good to go, imho. My temp sender only has two wires, which means the ground circuit is the engine block...if engine block is not grounded good to the computer....guess what...stuff happens, with a floating ground.

[Pushrod_V6]

:werd:

Sorry for not getting back to you guys, thank you for all your help earlier. I ended up putting in a new thermostat, which initially made my problems worse since the car was entering closed loop and stuttering like a crazy horse.

Well, one day I was talking about the car with another friend of mine and he asked me whether or not one of the ground wires was damaged.... :dunno:

Sure enough, I found one that wasn't attached just below the radiator cooling fan. As soon as I did that, VIOLA! Perfect.

Now I just need to put a door on it to pass PA Inspection.... Something about a 4"x1" hole they don't like.

[85_Ciera_Rebuild]

one of the ground wires was damaged.... :dunno:


Yes....got a pic of it....where it goes....???

[Pushrod_V6]

Yes....got a pic of it....where it goes....???

No, not handy - I need to change out the transmission pan gasket this weekend and I'll snap a pic of it then (if I remember - I'm going to put a post-it note on the dash now).

It came off the engine harness loom, and I found the eyelet still bolted (very rusted) to the radiator core support, beneath the driver's side cooling fan. As soon as I reattached and bolted, the problems went away. I really couldn't be happier with the car - at least the way it runs.... :)

[85_Ciera_Rebuild]

As soon as I reattached and bolted, the problems went away. I really couldn't be happier with the car - at least the way it runs.... :)

Yes...it would be nice to know what it was...color code...what it does...