Peakster's Geo Thread

Peakster · 01-22-2007, 10:52 AM

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My car has made an unexpected early arrival at the mechanic shop. I drove to school this morning with my usual driving techniques (high throttle loads at low rpm) and everything was fine.

An hour later after my class I got into my car to drive home when I immediately noticed that the Geo had extremely sluggish acceleration. If I let up on the gas it was fine, but unless I was doing 10% throttle loads the engine would simply misfire and it occasionally stalled when stopped at traffic lights, etc.

My "service engine soon" light blinked and I managed to use the almighty Scangauge to find the trouble code: P0303. According to my mechanic it means 'misfire on cylinder 3' so it could be anything really. In the end I parked the Geo in the shop parking lot (I had made an appointment for Thursday anyway for oil leaks).

The only other vehicular option I have right now is to drive my dad's '95 Silverado truck:

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It would probably get 9 mpg at this time of year (to make it worse, it's not compatible with the SGII). I'll most likely just wake up earlier and carpool with my dad and sister to university the next couple of days. It would be nice if I could see a FE improvement after the Geo is fixed.

rh77 · 01-22-2007, 12:11 PM

I'm not by any means a mechanic, but I had this happen in a controlled situation.

When I did the cylinder deactivation experiment, I essentially disconnect power to the injectors via a switch and wiring to each of the 2 injectors, leaving the other 2 alone. During operation, I got the same SG code for each cylinder (as they weren't operational).

I'm going to venture a guess that the #3 fuel injector or related wiring is fouled/failing.

At any rate, sorry about the breakdown -- it's always a pain

Regarding the truck, my folks old '92 Carbed 5.7L Chevy Extended Cab, Long-Bed 4X4 with the 4.11 rear-end was lucky to get in the double digits any day of the year. I'm thinking with the right driver, you could get in the low-to-mid teens with the '95 (US MPG). Good luck with the Geo and the truck!

RH77

MetroMPG · 01-22-2007, 12:50 PM

The Suzukiclone G10 3-cyl has throttle body injection, so I doubt it's fuel related. Kind of points to an ignition component (plug wire, plug, distributor cap). That's my guess!

3 people carpooling in a 9mpg truck = 27 mpg effectively, so it's not so bad.

Peakster · 01-22-2007, 03:56 PM

Quote:

Originally Posted by MetroMPG

The Suzukiclone G10 3-cyl has throttle body injection, so I doubt it's fuel related. Kind of points to an ignition component (plug wire, plug, distributor cap). That's my guess!

I just went back to the shop to collect my parking ID in the Geo for use in the truck. The mechanic already had the Geo in a bay and said that the distributor was wet (which made sense since I washed my car & engine bay yesterday). He said he was going to replace the spark plugs anyway because they were corroded.

On the bright side, he tested the compression and only cylinder #2 is lower than 100% (he said around 90%). Not bad for a car with over 150,000 miles. He also said that the car should be ready (oil leak fixed and all) by tomorrow morning.

Quote:

Originally Posted by MetroMPG

3 people carpooling in a 9mpg truck = 27 mpg effectively, so it's not so bad.

My dad always uses the Chrysler for commuting in and out of town. The truck is only used in those rare times of towing or hauling... or in my case when the Geo konks out

.

JanGeo · 01-22-2007, 04:59 PM

I had the original wires and plugs in my Geo to the end and had a lot of "fun" when the weather was damp (being near the Ocean) the wires would spark a lot through the insulation and give that engine misfire feeling when trying to accelerate until they would dry out. Lots of WD40 would help.

The middle cylinder low compression may be from the misfire washing away some of the lube on the cylinder and it may come back up once you run it some more.

MetroMPG · 01-22-2007, 06:31 PM

Except it was the #3 cyl that was misfiring.

The middle cylinder compression difference is more likely an exhaust valve issue. It seems to be a problem with these engines, possibly related to clogged EGR passages causing that cylinder to run hotter than the others, affecting the valve.

Search EGR at teamswift.net for more info.

rh77 · 01-22-2007, 08:35 PM

Good diagnosis Metro. I wonder what sensor, exactly, differentiates the the misfire in 1, 2, or 3. That would help determine the cause. I think the simple solution is the wet distributor.

Since I'm really learning about different engines, does the G10 port injection have one injector that feeds the entire manifold?

RH77

Peakster · 01-25-2007, 03:21 PM

I got the Geo back today and the car is all good now. Oil leaks are fixed, new plugs, and timing belt were installed. The mechanic said the timing was a bit off too.

No more driving the nasty truck!