Catalytic converters?

[fletchusmc]

Been enjoying my ZR-1 and driving as often as I can, but now having some running issues.

1995, stock with Corsa catback, Screamin Demon coils, and Livewires spark plug wires. 68,xxx miles.

Drove it to work Friday morning, seemed fine. About a 50 mile commute one way. Left work to come home and started running a little rough, loss of power, no difference with power key on or off. Felt like maybe some bad gas. Drove it a lot over the weekend to burn off some fuel. Put in a can of Seafoam and filled up with fresh gas. Drove it to work Monday and same thing. Tuesday morning was the same thing but coming home Tuesday it got worse. Didn't want to hardly rev. Idle so bad at stop light that dual mass was making noises.

Pulled plugs, all looked the same and replaced about 8,000 miles ago.
Checked ohms through wires and coils:
1-6 9.03k
2-3 9.3k
4-7 9.07k
5-8 9.00k

Didn't drive it the rest of the week. Saturday took it out a bit and not as bad, felt like something "freed up" a bit like it could breath easier. Rev'd easier, idle not as bad, still not perfect and still low on power. Got on it and got a exhaust smell, took a lot longer to get up in RPM's but it would.

Decided to go ahead and pull the converters to check them out as it seemed like an easy thing to do. After being under there maybe not so much. Looks like possibly 3 bolts won't be so bad but one doesn't seem to have any room at all.

So, does it sound like I'm on the right track or should I be focusing elsewhere? Can't see any messed up vacuum lines, don't hear any vacuum leaks. MAP and fuel pressure regulator lines are good. Went ahead and replaced fuel filter as well and no change.

[dredgeguy]

Have you changed out the injectors? Your issues are very similar to what I had when I purchased the car. Changing to stainless steel injectors took care of it. Found out 7 were bad and lucky I made it from CT to MD. You might also change the fuel filter.
Good luck and keep us posted.

[dredgeguy]

Sorry, you took care of the fuel filter..........now if the injectors are stock, you know where the problem is.

[We Gone]

Did you check the fuel pressure?

[fletchusmc]

Thought about fuel pressure, will go pick up a gage tomorrow and check that. I know injectors were a common problem on the earlier ZR-1's, but didn't think the later ones really had any problems with injectors?

[fletchusmc]

Got in the garage this morning and this is where I'm at.

Fuel pressure, cold, key on engine off 48 psi.
Idle 44 psi, stayed there as it warmed up.
Remove regulator vacuum line 53 psi.
2000 RPM 43 psi.

After shut down stayed at 48 for 10 minutes, disconnected pressure gage after that.

Took some catalytic temp readings

Driver's side
Front of cat 380F
Rear of cat 650F

Passenger side
Front 350F
Rear 460

Still making me think a problem with the cats. OR is it running way too rich on the driver's side and causing the cat to work harder and causing the higher temps?

[A26B]

I think you need to isolate the primary fuel pump by removing the fuse for the secondary fuel pump. The cold readings you observed would be the results for both primary & secondary pumps operating together.

The secondary pump will shut down after coolant temp reaches about 170F ( I forgot the actual number). You did state "stayed there as it warmed up." but actual temp is unknown so the secondary pump may still have been running.

Good news is there is not a significant injector leak.

I have no input on the converter temp, just the fuel pressure test.

I'm sure you will get it resolved.

[Marc Haibeck]

If it is still idling poorly I would approach it from that angle. It's easy to work with in the garage. You have good fuel pressure at idle. A clogged catalyst usually won't effect the idle. The faces of the catalyst substrates can be viewed through the oxygen sensor hole.

Do a spark test. The spark should be at least 1/4" long, blue and make a nice snapping sound.

[fletchusmc]

I appreciate the help so far. Life, work, and the holidays have kept me out of the garage lately. However, the Marine Corps is sending my girlfriend on an expense paid trip to Quantico for a week so I'm looking forward to plenty of garage time and will keep all of you up to speed on what I'm finding out.

[8cam]

Check the simple things first. With it idling, start pulling plug wires. If you find one where the idle doesn't change, you found your culprit. Check the spark on each plug wire too, but if you have a bad coil or wire it should be pretty obvious as soon as you pull the wire. I've read about Screamin Demon coils failing, and going suddenly.

[fletchusmc]

Had one of those duh moments this morning, hooked up a timing light and no fire on number 1, all other 7 were working just fine.

[Paul Workman]

Got in the garage this morning and this is where I'm at.

Fuel pressure, cold, key on engine off 48 psi.
Idle 44 psi, stayed there as it warmed up.
Remove regulator vacuum line 53 psi.
2000 RPM 43 psi.

After shut down stayed at 48 for 10 minutes, disconnected pressure gage after that.

Took some catalytic temp readings

Driver's side
Front of cat 380F
Rear of cat 650F

Passenger side
Front 350F
Rear 460

Still making me think a problem with the cats. OR is it running way too rich on the driver's side and causing the cat to work harder and causing the higher temps?

The fuel pressure raises a flag; sounds like one of the pumps is not working - or at least the symptoms are the same (as mine were).

With the ignition OFF, an ammeter connected between the positive battery post and the fuel pump diagnostic connector (the short red pigtail jutting out of the wire harness next to the diagnostic connector which is toward the middle, near the ECM).

Configuring the meter to read amperes...

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/Fuelpumpcurrentcheck004.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/Fuelpumpcurrentcheck004.jpg.html)

Connecting the meter to the fuel pump test jumper: RED LEAD TO POSITIVE POST, BLACK LEAD TO THE TEST PIGTAIL.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/Fuelpumpcurrentcheck001.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/Fuelpumpcurrentcheck001.jpg.html)

BOTH pumps are powered ON and you can measure the current. Each pump will draw about 4 to 5 amperes ea, for a total of 8-10 amperes.


http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/Fuelpumpcurrentcheck005.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/Fuelpumpcurrentcheck005.jpg.html)

While the pumps are running, you should measure about 53 psi (again w/ ignition switch OFF). If your current is about half of what it should be, and/or the pressure is not up to par, then pulling fuses (as Jerry suggested) will isolate which fuel pump is not working (NO pressure with the ignition ON).

As for injectors...anything is possible, but the 93+ cars had injectors that were alcohol tolerant, and less likely the issue...BUT never assume.

BTW, you should always check electrical coils (ignition and injectors too) when they are at operating temperature. A bad coil will often read normal resistance until they are heated up.

[fletchusmc]

The original readings I got through the wires and coils were with the engine cold. The car had sat long enough that all the plugs looked the same when I checked them. Yesterday I had started the car long enough to connect the timing light to each wire and found the number one was not firing. Turned the car off and pulled number one plug, could definitely tell it wasn't firing as it was really wet with fuel.

Will run the fuel pressure test again with pulling fuses, maybe have a fuel pump issue as well as no spark on number one. After the fuel pressure test I'll check the resistance through the wires and coils again as the car will be warmed up.

Emailed the former owner yesterday, he's going to look for the coils he removed when he replaced them with the Screamin' Demons. He had already given me the original plug wires and exhaust not too long after I bought this car. Figured I'd pull the plenum, go ahead and do the throttle body coolant bypass (to make it easier if the coil doesn't fix the number 1 no fire as well as when I follow Steve's repaint like he did to his recently, just want to fix this problem before I repaint to lower the chances of messing up new paint by multiple plenum pulls) and put the original coils back in it. Will check all the secondary vacuum stuff while I'm at it.

Of course as most of the people who know me can attest the hardest part for me will be to not let this coil replacement snowball into a "while you're in there" type of thing, especially since Lee just posted up ported injector housing and plenum!

[gbrtng]

A timing light? how 1950s ... Anyhow, you found the problem - the coil is a common part that NAPA should have.

[Paul Workman]

Of course as most of the people who know me can attest the hardest part for me will be to not let this coil replacement snowball into a "while you're in there" type of thing, especially since Lee just posted up ported injector housing and plenum!

Yeah, it was an epidemic, up here in FBI land. Most of the Zs up here have caught a dose of it.

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/Headporting1.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/tech%20files/Headporting1.jpg.html)

However, when it comes to racin', the Zs have taken home the bacon (team trophy) against all comers, 3 of the last 4 contests!

http://i185.photobucket.com/albums/x220/6PPC_bucket/Trophy.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/Trophy.jpg.html)

[fletchusmc]

Good news, definitely bad coil. Replaced all 4, started great, idles great, drives great, sounds great. Until you get close to 5k RPM, then no more and a brief check engine light. Chalking it up to first time plenum pull and didn't get something with the secondaries back together correctly.

From what I understand to get codes they show on the heater/AC display? If so that sucks because that's the only part of the car that wasn't working right as it just shows jibberish.

[fletchusmc]

All is well again. Pulled the plenum this morning and found one of the brittle plastic vacuum pieces had broken right at the barbs. Fixed that and drove her, rev limiter in 1st and 2nd so I'm happy again. I didn't realize how weak the coils were getting before the one finally quit as this drives and sounds like a different car now.

[A26B]

Great! I know that feeling well. Chased a bad coil for some time after I first got my Zee.