Last spring (over a year ago) I changed the plugs, Dist. cap & rotor, and plug wires on my '95 S10 Blazer (4dr 2wd).

Ever since then, it runs VERY rough when at idle (stopped or at a red light, etc.). I have checked to make sure I got all the wires going to the correct cylinders from the distributor cap. (I've now got 118,000 miles on the beast)

Then this last spring I made a cross country trip from Texas to Virginia... halfway through Tennessee, the Check Engine light came on intermittently... I took it to 2 dealers (Tennessee and Virginia) and neither could figure out what was wrong. One changed my thermostat,and the other charged me $300 to change 6-inces of vacuum line and to spray out the carbon from the intake.

The check engine light still came on intermittently for the trip home.. Mentally frustrating for me at that point....

After I returned to Texas, I replaced another 6 feet of cracked/falling apart vacuum lines.. but I still have a VERY rough idle.. I'm getting some dieseling when I shut off the Blazer, and when I start it up, I smell a DISTINCT smell of gasoline - and sometimes a rotten egg smell.

a) I had the catalytic converter changed about 2 years ago - I don't *think* that would be the problem. Though the rotten egg smell reminds me of that..

b) When changing the plugs/wires - I *did* get a couple of them swapped for a second. I fixed it immediately.. But could I have done any valve damage by starting it up with a bad firing order?

c) I changed the o2 sensor when I returned to Texas.. still rough & smelly (the Blazer - not me).

d) EGR valve was changed waaaaayyy back at about 50,000 miles - under Mfg Exhaust system warranty. Both dealers on my trip to Virgina told me that EGR valve couldn't be the problem I was experiencing - though to ME it gave the same symtoms - rough idle, almost wanted to die at low idle...

Would it be worth my time to simply get a timing light to see if my timing was knocked out of whack when I changed the distributor cap & rotor? Or does anyone here have any other suggestions? The code retreived by the first dealer was for a "lean condition". THough I know it wasn't running lean, as I was only getting 14MPG highway miles... I should have been getting closer to 20-22 MPG on the Hwy...

The Service Engine light no longer comes on.. but the mechanical symtoms are still here. Any ideas?

Thanks,
Rex S.
Richardson, Tx

 

if you didnt loosen the dist. itself when you ghanged the cap you shouldnt be out of time. although that could make sense with the diesiling and rough idle. it wouldnt hurt to check it though. check to see if any of your new wires are arcing on to something in there. as far as rotten eggs........................

 

Okie dokie...

I picked up a timing light at Harbor Freight - Not a bad deal at $24.95. THe Haynes manual says that I need to bypass the timing system by disconnecting a tan wire with black stripe from the distributor - yet it also says to leave the wiring harness connected to teh distributor...

For the life of me.. I can't find any wire going into the distributor that's tan/black stripe. Can anyone here give me a pointer as to where that wire is?

There are 2 wiring harnesses plugged into the lower right hand side of the distributor (when looking at the engine from the front of the Blazer).. but the distributor/cap is behind the engine,a nd just about impossible to (a) see anything back there.. and (b) get my hand in there to pull a wire, even if I were able to see it...

So - where's that mysterious tan/black striped wire?

Thanks,
Rex

 

this could be an o2 sensor problem. if the sensor is bad, it may send a code stating "too lean". it will then try to richen up the mixture as much as possible. pull the sensor out and see if it is contaminated. if it is, replace it. if you havent done it yet and you have that many miles, then its about time to do it anyways.

 

Yeah - that's the first thing the guy at AutoZone told me as well... So I did replace the o2 as soon as I got back to Texas from Virginia (this last March). Granted.. I have not seen the service engine light since then... But I haven't driven for any extended period of time (i.e. 4+ hours at a time) since then either... but it still runs rough at idle, and diesels when I turn off the ignition...

On a whim, I jumpered my freaky OBD (OBD-I Blazer, but an OBD II connector) connector to see if I had any codes in there... All I get are the 12 code over.. and over.. and over... and over...

Still, I'm unable to find the mysterious tan wire with a black stripe to check my timing (by disabling the timing system)... But I'm wondering if it could be a fuel delivery problem. It's just kind of got me in a quandry... I'm gonna change the fuel filter again, too.. Cheap, and needs to be done periodically...

Something I noticed this morning when I fired up the Blazer... The exhaust seems to have a prety consistent "fft ffft ft ft ft ft ffft" kind of sound emitting from the exhaust pipe.

This weekend I'll see about replacing the plugs again.. and will see if they seem to be sooty... I need to pick up a swivel adapter for my socket wrench though. Several of the plugs are a booger to get out and install!

Rex S.
'95 S-10 Blazer 2WD 4Dr

 

sorry, i just noticed that you changed it in your first post. im not sure about that wire though. ill see if i can find something out tomorrow.

 

I had a great post, however I got an error message saying I didn't have sufficient permission. Somehow I was logged out and logged back in as a guest. Arrggggg

I'll try to recreate it.

When is the last time you replaced the air filter?
Have you ever replaced the IAC (idle air control) valve?
Get the ignition control module tested. Realatively easy to take off and most autoparts stores can test them. Call first, AZ didn't have the right wiring harness, however O'Rielly's did.

Egg smell could be your charcoal canister, fuel canister, or wahtever you want to call it. Look it up in the Chilton/Haynes manual. They do a good job covering it.

I never found the wire either, although it sounds like you put more effort into it then I did.

Simple test for O2 sensor. Disconnect the wire. IF the engine smoothes out the sensor is bad and needs replacement. The pcm uses the signal from the O2 sensor to tune the engine. When it doesn't get the signal, it goes into a default mode. Not great for gas mileage, however it will tell you if the sensor is bad or not.

 

March of this year - just before my trip to Virginia

IAC: Not that I'm aware of. I'll check on the ICM as well this weekend, and will report back...

Will do...

Thanks for the suggestions! I'll go through and see if anything seems to do the trick...

 

That tan w/black wire your talking about is under the carpet on the passenger side floor on my '93 blazer. Sometimes it is on the passenger firewall wiring harness. Disconnecting this wire puts the ignition in "base timing" mode and will set a code, so clear the code after your done setting the timing.
It really sounds as if your engine needs to be decarboned, mine has a digital EGR valve and ALL of those EGR valves are notorious for getting little pellets of carbon trapped in the pintle area, thus resulting in erratic idle, stalling, check engine light coming on and going off and a distinct "rotten egg" smell". The EGR valve is easy to remove and depress the pintle with a small screwdriver and the carbon pellet will fall out. While the EGR valve is off (if you have access to it), blow compressed air in the EGR hole in the intake. This will blow any other pellets or chuncks of carbon out of the intake and passage.

 

Under the freakin' carpet?? Geez - no wonder people rag on the Hanes manuals for inaccuracies and misinformation...

On another note.. Yesterday, I opened the hood, and removed the air intake (air filter housing) & disconnected & tested the air temperature sensor. Filter is clean... Sensor thermister working properly... It still runs rough - especially when I put it into drive, with the brake on.

I'll check the wiring harnesses and wires under there this afternoon... And de-carbonize the EGR as well...

Thanks,
Rex