After not having a metro for about 6 months, I just bought a '99 4 cyl automatic. This is just like the '96 I last owned. The engine runs rough and accellerates slowly. No check engine light. I don't have it home yet, but i think I'll make sure the timing belt hasn't jumped a tooth.

anything else you folks recommend for diagnosing this problem?

I'm sure glad to be back active with this forum!

Sounds to me like either an exhaust restriction or worn out ignition stuff. Cap, rotor, plugs and wires. Check the timing, air filter, etc. Check for vacuum leaks. Make sure the pcv system is functioning properly. Post back. If its not any of that, could be a dirty fuel injector, maladjusted TPS, blah blah blah

check the compression

Also recommend taking it to a repair shop you trust and have them hook up their expensive scan tool to read all the data coming from the ECM/PCM. It can be a real time and money saver.

Much agreed with Crv and Sas ^^^

I have a scantool that hooks up to my laptop and reads and clears OBD2 codes. When you say... "have them hook up their expensive scan tool to read all the data coming from the ECM/PCM"....do you know if its more sophisticated than what I already have? if so, would I have to go to the Chevy dealer to do this?

I'm kind of a cheap bastard...hence the '99 metro...

Well, OBD II is much better than OBD I. I think there are far more codes defined/available (and therefore the number of tests) for OBD II. My Metro is a '95 and is OBD I. Repair manual says there are 25 parameters being sent out by the ECM (for 95's, yours may be different):

Engine Speed (rpm)
Desired Idle (rpm)
Eng. Cool Temp (deg C/deg F)
Intake Air Temp (deg C/deg F)
Throttle Position (volts)
Throttle Angle (degrees)
MAP (kPa, Volts)
BARO (kPA, Volts)
Heated O2 Sensor (mv)
O2 Activation (Activate/Deactivate)
Spark Advance (degrees)
Injection Pulse Width (msec)
S.T. Fuel Trim (counts)
L.T. Fuel Trim (counts)
IAC/ISC Duty (percent)
Idle Switch (On/Off)
Park/Neutral Position (P-N--/-R-DL)
MPH / km/h
Fuel Evap Purge (On/Off)
EGR Solenoid (On/Off)
Electric Load (On/Off)
A/C Switch (On/Off)
Power Steering SW (On/Off)
System Voltage (Volts)
Rich/Lean Status (Rich/Lean)

And gave expected range for a car at idle/warmed up and healthy.

I wanted to see this data so started looking around for an affordable ($100 - $400) scan tool. All the ones I looked at couldn't read the data except for Vetronix Tech I's, Tech II's and Mastertechs. (Vetronix Tech I is what was mentioned in the repair manual.) But these new were $2000 to $5000! OTC, Autoxray and Actron scanners wouldn't read the data stream. I was able to get a Vetronix Tech I on eBay recently for several hundred bucks. It displays all the data. (Vetronix stopped making Tech I's several years ago.)

I feel the above is really useful for OBD I cars, but OBD II may be a different, and better "story". Maybe others with more experience could offer their thoughts on the subject.

And to finish answering your question, yes, going to a Chevy dealership you trust should work. And also an independent, trustworthy repair shop that informs you they have a Vetronix Tech I, Tech II or Mastertech tool.

I just got the car home after about an hours drive. The engine hesitates and stumbles. The CEL was on and when I got it home I checked it with my scantool. The code was P0300, random multiple misfires. The records that came with the car show the plugs and wires replaced within the last 2 years. Any history of this code with metros?

Mystery solved. I pulled the plug wires while it was running and both of the external wires coming from the two coil packs were arcing like crazy. It was quite the light-show. I replaced the wires and all hesitation problems are gone. The lady I bought the car from said her mechanic replaced the spark plugs but couldn't figure out what the problem was. Wow...this is why I do all my own mechanical work. Sometimes it's the simple things...

The only other mechanical issue is an occasional clunking sound caused by the exhaust pipe right behind the converter bumping against the sway bar. It looks like the bend in the pipe is in the wrong place. It might also be a weak motor or tranny mount I suppose...any thoughts?

Sure is nice driving around in a Metro again....

...Sometimes it's the simple things...


I have learned over many a car that one of the FIRST suspects to interogate in the case of a misfire are the plug wires. Especially with the fuel injected/computer controlled vehicles we have today. Glad ya got it running smoothly!


The only other mechanical issue is an occasional clunking sound caused by the exhaust pipe right behind the converter bumping against the sway bar. It looks like the bend in the pipe is in the wrong place. It might also be a weak motor or tranny mount I suppose...any thoughts?

Sure is nice driving around in a Metro again....

Get the car on stands and look for evidence of trauma to the pipe. Look for broken hangers in the exhaust system, particularly those found near the muffler and rear of the system. Bad mounts will usually enhance the inherent vibration in these cars. They are inspected easily enough by looking for cracks and/or seperation in the rubber, for the rear mount you may have to peel back the rubber sides to view the mount itself. Note whether or not it is possible to position the motor via some appropriate leverage in such a way as to create what looks like correct clearance between the exhaust and the sway-bar. That is to say, see if you can "prop" the engine up a bit from behind, or otherwise rotate it toward the front of the car. If you can jossel the engine in such a fashion I'd suspect that the rear mount is dust.

-MechanicMatt

I propped the car up on all 4 corners so I could crawl under and make a thorough inspection. It turns out one of the rubber hangers was really soft and had stretched out a little. I replaced it and it now pulls the exhaust enough so no more rattling.

Glad you found the problem. Just to add my own experience on the topic, the muffler shop I went to used the wrong sized rubber mount near the muffler, and even though I had them adjust it once, the muffler continued to hit the control rod until the exhaust pipe broke away from the muffler. Good thing they have a lifetime warranty, and since they fixed it last year, there hasn't been anymore banging around. And oh yeah, the more weight on board, the more it clunked.

Jai