Hi Folks, New on the forum. Found it recently while googling to fill in the gaps in the Haynes maunal.

I have a 1995 SW2 with a 5 speed manual transmission that we purchased new. A couple of years ago it failed emissions testing on N0x and after some investigation I found there was no compression in cylinder 3. (130,000 km, ho hum...) For various reasons the vehicle sat for a couple of winters and this winter I pulled the engine and tranny and replaced a burnt exhaust valve. Everything is back together with no spare parts, it fired up first time seems to run fine. However when I now get it tested it fails on HC.

OK so this means incomplete combustion. Which means that there is a problem with the spark or the fuel.

PCM Error Codes: None

Spark:
- Plugs new
- Cables a few years old, metered them out and no significant resistance.
- Firing order on iginiton block from left to right is 4-1-2-3
- Ignition block seems fine, have not done a spark check as this is tough to do solo and I don't really think this is the problem area.

Fuel:
- Injectors, not tested - not sure how I would do this
- O2 sensor, its about 3 years old (jobber part), When the engine is hot I can measure voltage coming from it. The Haynes manual says the voltage should be between .1 and .9 volts. I seem to be getting about 1.3 volts on my old analog meter. Is this any indication that it is faulty or is it just telling me that the HC level is really high? Can I use this as a method of measureing whether my changes to the system are having any effect? (swap a part and measure the O2 sensor voltage to see if the HC levlel is being effected?) When I measure the voltage I am disconnecting the sensor in order to probe it with the volt meter. Presumably the PCM sees 0 volts and does something (treats this as a cold startup state or?) Is this a valid way of testing or not?
- EGR, When I tore the head off, this thing was caked in carbon. I cleaned it off with a wire wheel and blew it clean with air. The little diapragm looked like it was operating, but not 100% sure. This is is an expensive part to change so don't want to until other things are exhausted.
- MAP, When the head was off I took the throttle mechanism off the throttle body and the inside was caked in sticky black soot. As I had not dissasembled the injectors I did not want to go to town cleaning this out so pretty much left it alone. Given the state of the inside of this I put in a new MAP sensor today, but am not sure whether this has really changed anything.
- ECT sensor, I have a new one as they are cheap, but am not convinced there is anything wrong with the old one. The 95 SW2 has a second sensor above it that looks very similar to the ECT except there is only 1 wire going to it. Can someone tell me what this is?
- Catalytic converter, original and probably a bit sooty.

So any comments on how to trouble shoot this would be appreciated. Particlarly any comments on any tricks I can use to see if my fixes are having the desired effect before going in and getting tested again. (Voltage change on the O2 sesnsor for example?)

TIA bvd

 

- ECT sensor, I have a new one as they are cheap, but am not convinced there is anything wrong with the old one. The 95 SW2 has a second sensor above it that looks very similar to the ECT except there is only 1 wire going to it. Can someone tell me what this is?

Yep, I can ... it is the sending unit for the temperature gage on your dash ...

 

1) Replace ECTS with brass replacement. Replace ECTS connector as well. Failed ECTS causes car usually to run way rich -- thus more HC emissions. The 1 wire sensor is the temp sensor for the dash gauge.....

2) Replace O2 sensor with Denso replacement -- Bosch replacement did weird stuff to my 95SC2 and the universals are universally pointless when you can buy the right part.

3) Soak the EGR in choke or carb cleaner and make sure you also clean the ports where it attaches. The EGR pintle must be able to move freely. Make sure the EGR solenoid is functioning or the EGR will not actually be moving. Usually this shows up as a severe drivability problem---which you didn't mention -- but thought I'd throw it in for good measure.

4) Clean the throttle body with throttle body cleaner. Sounds like you had an oil burner there....between gumming up the EGR and recirc'ing back through the throttle body, you've got carbon built up all over the place.

5) Injectors should be fine unless you previously had problems with them.
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Sounds like it was a good oil burner.......What are the current compression readings? If you did not replace the valve guide seals, valve seals, or do the rings (none of which you mentioned doing), then you are still fighting an oil burner.
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Change your oil right before inspection to remove the dissolved HC's added to it from blow by gases which are "dissolvled" and recycled throught the throttle body. And use 87 octane dried out with gas line antifreeze.

If your plugs are getting oil fouled, change them right before inspection as well.
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The above advice (notice the emphasis on removal of built up carbon and the emphasis on replacement two of the most critical sensors in an S series vehicle w/r/t emissions) should go a long way towards addressing your emissions issues and will have the added benefit of a better performing car......

 

Thanks for the replies guys...

ECTS connector and O2 sensor arriving this afternoon. (Have the
ECTS already) I'll get them in tomorrow.

EGR:
No real drivability issues. Some occasional weird stuff like when coming to a stop after a series of hard down shifts (decelerating by using the engine) it won't idle and stalls. It does start up right away. That's the only oddity.

The EGR mating surface was not flat with the manifold when I pulled it off. They used some silver gasket goop on the gasket. Looked a bit like muffler cement in color. Can you tell me what kind of goop I should be using to install this with? I am pretty sure I don't have the right type on at the moment.

So its safe to soak this thing in carb cleaner then. The little diaphragm thing seems move back and forth again. It was completely caked before hand. I'll pull that tomorrow as well.

Throttle body:
I left this alone as I was worried about knocking carbon into the injectors and intake valves. Is this something I need to be overly concerned about when cleaning this out?

Compression and Oil:
Yes, its always been an oil burner. Thought this might be a Saturn thing. Compression 200, 196, 194, 200. All valves cleaned and lapped, and valve stem oil seals replaced. I did not measure the valve guides, as this would be a machine shop task. I mic'd the cams and plastiguaged them and they are definitely at the edge of the useful range in places. The worn journals looked like a new head was not out of the question. The dealer wanted way too much for one. I wasn't confident about a jobber refurbished one, based on how these things are put together. (Sorry, steel running in aluminum journals has got to be an on going issue...) So I stuck with the original head. I had decent compression in the other 3 cylinders before this job, and the cost of looming parts kept me out of the bottom end. I had hoped that the oil uses was a valve stem seal issue, but it appears not to be. If this is not a Saturn thing then I am guessing that the oil rings were originally installed upside down in the factory. Lucky me... I did drop the pan and clean it out, so oil is very clean. I have less than 50 miles on this since the re-assembly and plug 1 is already looking oily...

So my plan was to run it for a few miles on cheap oil and a new filter to clean out any crap I left in the engine, and then to dump it and refill with synthetic in hope of babying the tired head along...

 

1) Stalling upon deceleration can be attributable to a sticking or sluggish EGR. I meant to soak the inside of the EGR -- not dunk the entire thing in carb cleaner -- sorry if that was unclear.

If you are careful, you can chip away at the EGR carbon buildup with a small screwdriver -- just don't wreck the pintle. Remember that what moves when cold may stick at operating temp with all that gunk in there.

2) I believe EGR should mount flush with a pre-formed gasket in between the egr and the manifold-- I've never seen goop used to seal this (I have a 95 and 97SC2; I have removed both EGRs and seen only a preformed gasket in between. I don't think you should need any goop. Hopefully the EGR mating surface did not get messed up during the wire wheel cleaning step. Though from your description, it almost sounds as though it has been pulled and cleaned before (and possibly compromised at that time).

3) If you are concerned about carbon chunks clogging the intake or injectors, simply remove the throttle body from the intake and clean it on the bench. SInce I can't see how gunked it is, bench cleaning would be the safer option to me. Be sure not to damage the gasket when you remove it. If you end up with an erratic or high idle after you put it back on, it's likely a vacuum leak at the throttle body/intake mating surface. You can spray throttle body cleaner around the gasket area while the car is running -- if the rpms change, you've found the leak.....

4) Compression looks ok and even across the cylinders. The valvework you did will extend the useful life of the head s Valve guide seals would have helped quite a bit long term, but life goes on.......

5) The oil control rings in the S car engines are known to build up a varnish on them and consequently they stop floating and seize in their channels, which negates their ability to sweep the cylinder walls. Hence the S car's reputation for being oil burners.

You can try an MMO (Marvel's Mystery Oil) piston soak to see if you can get them freed up --- search any saturn forum for MMO or piston soakand you will find step by step directions on how to do this. Works for some, not for others.....

Personally I would try to pass emissions after addressing the above items first ---then try an MMO soak to address long term oil consumption issues --- once you are again legal to drive......

Also, keep in mind that with the amount of oil being burned, the throttle body and EGR cleaning will need to become more frequent to keep the car running well.....

Hope this helps

 

Thanks for that derf

EGR:
No gunk left on the surface of that as I aggressively cleaned it. Only question is whether I damaged it or it was already damaged. If I replace do I need a Saturn part for this or can I use a jobber? I am up in Canada and the parts are not cheap here. The new O2 sensor was about tripple the jobber part.

In terms of fit EGR to manifold, the car was dealer serviced up to a few years ago, so the goop was either factory or put on at the dealer shop. I don't remeber ever paying for a new EGR so I am guessing factory. Its not close to being true, definitely not caused by the wire wheel. The two pieces wabble around without a gasket. I had pulled the throttle body off the manifold and the same goop had been used there.

Throttle body:
My mistake in terminology, the intake manifold where the TB is bolted to is still gooey. I thouroughly cleaned the TB in a solvent bucket when I had it apart, and blew it out with air to make sure the little ports were clear.

Valve guide seals:
The valve guide seals were done. In your previous post you also mention valve seals, not sure what you mean by this?

Oil Consumption:
Aha! OK, I'll look into that after I get it through testing.

 

EGR and throttle body mating-- weird weird weird. Maybe the goopy stuff is what's left of the pre-formed gaskets that were there?

Have you ever had the EGR or throttle body serviced at all since you've owned? I know you said not replaced, just checking.....

No personal experience with aftermarket EGRs on S cars.....anyone? anyone?

PIX
Can you post a pic of the bottom of the egr valve and the port where it mounts?

And one of the goo where the throttle body mates to the intake?
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Anyone have any ideas as to what this goo is ?
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Valves: My bad ---I kinda meant valve seats -- you said you had the valves lapped so they should seat properly again. Glad to hear valve guide seals were done.

 

EGR and throttle body:
I think that's it. I just pulled off the EGR again and the goop I put on seems to have 'mushed' the gasket into a simmialr state to the previous one. It looks like old goop, but is mostly the gasket material adhering to the surfaces. Here's what it looks like after juste removing it again. This was completely clean less than 50 miles ago....

 

Not sure how to post multiple pics on this site so I am doing them as separate messages. This pic is what the EGR looks like afer I have cleaned it up again...

 

The mating connection on the manifold. When I but the EGR on the manifold, it rocks (wabbles) along the axis between the two bolt holes. Maybe as much as 1/32" . Note the new ECTS connector in the background!)