1995 mtx intermittently dies while driving

[Constant_mess]

I'm having some problems with my 1995 sho mtx with 168k miles. I bought it back in the middle of July and the previous owner said that there was a recent minor leak from the back right of the engine. He was pretty meticulous about maintenance giving me old parts of the things he replaced but most of it was minor stuff besides the clutch and said that he did a front 60k at 120k. It ran fine for the most part for 2 1/2 months. The only problems during that time was that every few days when starting the car the rpms would be bounce around instead of steadily idling it would go away once I put it in gear and started driving. The other thing during that time was that sometimes under 4k rpms it would be slow to speed up under wot like it was being bagged down and the he oil leak wasn't bad until the couple of weeks before the first time it broke down and I used about 5 quarts to keep it topped up. When it broke down the first time I was on the highway in 3rd gear going to shift into 4th when the tach dropped down to 500rpms with the engine still running but had no power and then it started bucking and I had to put it back in gear so I could get over to the shoulder since I was in traffic and during that it was bucking pretty badly until it shut off completely. I opened the hood to see if there was anything immediate that I could notice that would have caused the breakdown I didn't see anything but I did smell some burnt coolant from the passenger side of the engine. I had it towed to the shop since I thought my coworker would be able to fix it and he replaced the fuel pump. After that though the sho still wasn't running right. Every time he scanned it on KOEO it would say code 11 and on KOER it would give code 548. It would either start up immediately or take a few tries to start it once it was running it would either be fine or misfiring out of the 2 cylinders on the passenger side of the engine bad enough that the car was bucking. When it was running fine it wouldn't have any power when driving it through the whole rpm band or it would gain some power after 4k rpm until the tach would drop out and the engine would be running like it was idling until you would do anything to car and then it would stall. When restarting after it stalled the car would take a while to restart to where it would backfire when finally starting to run or it wouldn't even crank. The other day my coworker when he was looking at it jiggled the connector at the top of the engine to the crank sensor and after that the sho ran fine for the weekend only twice where I drove it cold that it had the no power through the rpms and both times after jiggling the connector a little it would be running fine again. It broke down again on the way home from work yesterday where I was merging onto the highway and right after I finished merging the thermostat had opened up and then tach dropped out again, no power and it stalled once I turned the wheel with no power steering to pull onto the shoulder. I opened up the hood I could smell some burnt coolant and jiggling the connector didn't work and the sho wouldn't crank at all. So I had it towed back to work and I haven't been able to look at it since. I figured asking here would be a good way to get it running again.

 

[luigisho]

I can't absorb all of that chapter. Code 548 does not exist as far as I can see.

So, where is the oil leak?

Did the car overheat? Did the coolant leak out or bubble out due to overheating?

You can check your codes with a paperclip or jumper wire with instructions and diagram here. Try pulling them again.
https://web.archive.org/web/20080617184612mp_/http://www.shophoenixproject.com/eec/eec.htm

As an aside, any time the car stalls (sensor error or other reason) a code for fuel pump will get triggered. This does not mean there is a pump issue.

 

[haydenm315]

Man bro, your add is worst than mine!

1. Bogged down under 4k sounds like an issue with secondaries stuck open. They're vacuum powered around the back center of the intake manifold.
2. The tach jumping around sounds like the CPS going bad due to leaking coolant at the pump.
3. The plug well seals are notorious for leaking and eventually causes misfires. Pop a plug wire and see if there's oil.
4. gotta find that oil leak. You're doing ok if you get 700-1000 miles out of a quart.

 

[zoomlater]

pull your codes using the paper clip method that luigisho mentioned and report back

 

[NoSlo]

The tach "dropping out", quickly dipping to zero, while the engine is still revving, points 90% to the camshaft position sensor, (with a small possibility of a DIS module fault or wiring). Although it's not supposed to, this will often cause engine running problems if it is intermittently working. The failure of the CPS means the engine can't figure out when to fire when starting and will guess - which make take several attempts before the engine will start from the key. If you unplug the CPS, then you will still have the starting problem, but the engine should run OK after this.

If there was simply a problem with maintaining idle, like RPM drops too low or even dies when you don't have your foot on the gas, or oscillates like you describe, that first points to the idle air intake valve, which is how the computer keeps the idle up.

With symptoms like loosing 1/3 of the power even when accelerating, you could have a bad sensor, but without codes, one must first suspect misfire, the biggest cause being oil in the spark plug wells causing a short. Clean all spark plug wells, blowing wells out dry with an air compressor and swishing the wire end in gasoline to clean it out. Oil in the wells indicates leaking seals, replaced during upper 60k service if the car is maintained.

 

[Constant_mess]

We tried to pull codes a few times over a few days and it never gave any codes. I plan on trying again when I can pull it into a empty bay at work and then check the sensors and pinpoint where the leak is from since I tried to look before but I didn't have time to fully look. I've been looking at threads over the past few days on here and I think I'll have to do the full 60k since besides the front 60k that the previous owner mentioned doing at 120k I don't know what else has been done.

 

[luigisho]

Pull the spark plug wires and get a look to see if oil is fouling out ignition. Track down oil leaks to source. You have another vehicle to get you around?

 

[rubydist]

Man bro, your add is worst than mine!

1. Bogged down under 4k sounds like an issue with secondaries stuck open. They're vacuum powered around the back center of the intake manifold.
2. The tach jumping around sounds like the CPS going bad due to leaking coolant at the pump.
3. The plug well seals are notorious for leaking and eventually causes misfires. Pop a plug wire and see if there's oil.
4. gotta find that oil leak. You're doing ok if you get 700-1000 miles out of a quart.

Correction to item 2 above:
The crank position sensor has absolutely nothing to do with how the tach reads. That is from the cam sensor. As NoSlo pointed out above, a sick cam sensor can make the engine run like crap. So, since they are not expensive, I would just change the cam sensor and see what that changes.

All of the other advice above is sound.

 

[Constant_mess]

Is there any o rings that you need when you change the cam sensor? And for a replacement sensor this one will work right?

 

[NoSlo]

Is there any o rings that you need when you change the cam sensor? And for a replacement sensor this one will work right? View attachment 16531

It looks like that, but that's not a Delphi part #. Here: https://www.rockauto.com/en/catalog...138968,ignition,camshaft+position+sensor,7192

You do not want to seal the sensor, it just bolts on with two 5.5mm bolts. If there weren't stuff in the way, it would be a two minute job.

 

[FastCAD]

5 quarts of oil is not a minor leak. Smelling coolant is also bad news. The statement about regular maintenance and recent 120k service at 165k sounds like a myth unless it was 265k miles ago.
That said; a '95 mtx in good physical condition is a desirable find but you are probably facing doing long overdue maintenance that was never done.
Cam sensor: pull the connector off and start the engine to see if there is any change. It will probably take about 3 tries to start but it should start and if there is a change then the cam sensor is bad.
Double check where that coolant leak is coming from. If it is just a hose (u are in luck). If it is leaking from the weep hole below the water pump then you are looking at a new CPS and water pump. Delete the old codes from the ECU so u don't get off track and hopefully get new codes for other problems.

This seems like just the beginning. I don't know what u paid for your ride but u might want to re-evaluate if u should go down this hole before you get in too deep but there is plenty of support on this site.

Best to U

 

[BaySHO Performance]

You might want to familiarize yourself with Wiki SHO. There's a huge amount of info there. For instance:

http://wiki.wikisho.com/wiki/EEC_Self_Test_Procedure

Tach dropping to zero points to the camshaft sensor. Run your finger along the bottom of it to see if there's any oil there. Parts I use:

Camshaft Sensor (Duralast) F134 Autozone
Cam seal (National) 1213N O'Reilly

I've had at least 22 cases where the spark plugs have been completely immersed in oil, but the car has always run fine. Doesn't do the wires any good, though.

Observe that the secondary butterfly valve tabs are down engine off, meaning that the secondaries are open. Start the engine to make sure they are now closed with the tabs up top.

Bogging down under hard acceleration indicates a vacuum leak or dirty MAF. I've had several cases where this happened. Car runs fine under gentle acceleration each time.

 

[NoSlo]

We tried to pull codes a few times over a few days and it never gave any codes.

This is not a symptom to overlook.

First verify the bulb is not burned out. Turn the key to the "run" position without starting the car, "check engine" should be one of many lamps illuminated.

Then, identify the EEC-IV connector at the passenger firewall side of the engine, and note that it is separate from the identical-looking ABS test connector, which is usually located 4" further to the driver side.

Connect these two pins, ideally with a short piece of stranded wire with male spade terminals crimped onto the end:


Turn the key to the ignition "run" position. Watch the "check engine" light now, it should behave quite differently, and you should hear some activity from the engine compartment as the PCM performs some tests, and then flashes the codes that can be translated using the instructions here: http://yamahasho.com/eec/eec.htm

If it does not perform the KOEO diagnostics and test code readouts, that is a big problem. You can clean the ground connections at the strut tower and battery terminals, reconnect (unbolt and re-bolt) the ECU connector, but any properly-functioning SHO computer will give you codes.

 

[Constant_mess]

The cel is functional it was that when we did the self test it would say that everything was fine when it's clearly not. The last time we tried to pull the codes last week while my coworker was looking at his scanner he saw that the connectors for the dis were loose and we ziptied them in place since the plastic clips are worn out so it's no longer misfiring.

 

[Constant_mess]

You might want to familiarize yourself with Wiki SHO. There's a huge amount of info there. For instance:

http://wiki.wikisho.com/wiki/EEC_Self_Test_Procedure

Tach dropping to zero points to the camshaft sensor. Run your finger along the bottom of it to see if there's any oil there. Parts I use:

Camshaft Sensor (Duralast) F134 Autozone
Cam seal (National) 1213N O'Reilly

I've had at least 22 cases where the spark plugs have been completely immersed in oil, but the car has always run fine. Doesn't do the wires any good, though.

Observe that the secondary butterfly valve tabs are down engine off, meaning that the secondaries are open. Start the engine to make sure they are now closed with the tabs up top.

Bogging down under hard acceleration indicates a vacuum leak or dirty MAF. I've had several cases where this happened. Car runs fine under gentle acceleration each time.

I think it's a vacuum leak since I noticed a whine coming from the passenger side when I was driving it over the weekend before it broke down again. Where are the butterfly valve tabs so I can check if they are operating like they should?

 

[BaySHO Performance]

I think it's a vacuum leak since I noticed a whine coming from the passenger side when I was driving it over the weekend before it broke down again. Where are the butterfly valve tabs so I can check if they are operating like they should?

Unlikely that the passenger side is a vacuum leak. Most of the vacuum hoses are on the driver's side. Might be a worn pulley bearing.

Look at the following pic. You will see one of the butterfly valves between the secondary runners for #1 and 2 cylinders. The tab is right above it. It can be lifted by hand. Another valve between the #5 and 6 cylinders at the front. Start the engine and make sure that the tabs are now up, indicating that the secondaries have closed. If not, may be a vacuum leak in the tubes under the intake.

 

[FastCAD]

The cel is functional it was that when we did the self test it would say that everything was fine when it's clearly not. The last time we tried to pull the codes last week while my coworker was looking at his scanner he saw that the connectors for the dis were loose and we ziptied them in place since the plastic clips are worn out so it's no longer misfiring.

It's possible that u don't have any new sensor codes (big plus) and that your problems are purely mechanical.
The water pump will make a "whine" on the passenger side. Use a long screwdriver to your ear to verify this before u lose that CPS.
The oil leak at the rear of the block could be a valve cover gasket or an oil sensor at the lower right. If u get the SHO on a lift u should be able to find the leak.

 

[luigisho]

Pretty silver intake runners on that one Nick.

 

[BaySHO Performance]

Pretty silver intake runners on that one Nick.

Thanks. Lowell Galliani's '89 that had been sitting outside for 12 years with a bad clutch. A huge mess. 10 months to restore and upgrade it in 2014. The biggest job I've ever undertaken. 170 page write up (however lots of pics) here when you have a couple of hours to waste, LOL, but lots of tips in it:

https://www.dropbox.com/s/oznjuoz220b330m/Galliani Writep.docx?dl=0

Sadly Lowell passed away last May. I'm in touch with his son who now owns it.

 

[TornadoHands]

Thanks. Lowell Galliani's '89 that had been sitting outside for 12 years with a bad clutch. A huge mess. 10 months to restore and upgrade it in 2014. The biggest job I've ever undertaken. 170 page write up (however lots of pics) here when you have a couple of hours to waste, LOL, but lots of tips in it:

https://www.dropbox.com/s/oznjuoz220b330m/Galliani Writep.docx?dl=0

Sadly Lowell passed away last May. I'm in touch with his son who now owns it.

this write-up is great stuff, wow. sad about the owner, i hope his son appreciates the car!