I've been having a performance issue on my Tracker that has got me confused. I'm hoping that someone might think of something I haven't.

Here's the situation - Over the last month or so, my '01 Tracker (2.0L-5 speed) has had intermittent performance issues. Some days it runs great - peppy, good fuel mileage, etc and other days it's a royal dog and gets poor mileage. I've switched gas stations, tried fuel injector cleaners, new air filter, etc and have not seen any effect on it. I had the #1 O2 sensor fail this summer and replaced it. It's not throwing any trouble codes, but I suspect that I've got a faulty sensor somewhere (maybe the #2 02 sensor?). The plugs are less than a year old (Bosch Platinum) and the engine isn't misfiring. The gas mileage has varied between 24 to 28 mpg without any rhyme nor reason. It's almost as if my car is bi-polar: some days it ready and raring to go and others it just doesn't want to get out of bed.

I've toyed with the idea that the catalytic converter may be blocking up but I'm not willing to shell out the cash needed to replace it unless I'm sure it'll help.

Does anyone have a clue as to where I should look next? 

David

The plugs are less than a year old (Bosch Platinum) and the engine isn't misfiring.

It's your problem! Never mix Bosh and Suzuki! Try Ac delco or ngk!

Could be a bad connector on a temp sensor fooling the ECU into thinking the engine is cold and pumping more fuel in.

Could be a bad connector on a temp sensor fooling the ECU into thinking the engine is cold and pumping more fuel in.

You might have something here - I've had other issues that I suspected was a temp sensor, but they would clear up before I got to check it out. I'll look into that tomorrow.

Thanks!

Don't discount what Fredo said about the Bosh plugs - I had problems with those after about 20k miles.  I've run cheap NGK's without a problem since.  I'm not saying it's your problem but those plugs don't mix well with the 2.0 engine.  When I removed them they were covered in grey soot.

Ok - I'll pull the Bosch's and drop some NGKs in. I've managed 30,000 miles on these - man I was hoping to get more than that. Really annoys me - I've had really good luck with Bosch's in my other cars. I wonder what gives in the 'Zuki engines?

David

 

OK - NGKs in!

I was surprised when I pulled the Bosch plugs. The tips of the plugs looked OK, but the rest of the plug was covered in dark sooty deposits (kinda like they were running rich). Does that sound consistent with what you found on your Frank84? Haven't taken it for a spin yet, but it does sound better with the new plugs in.

Update.....
HOLY SNOT! I honestly did not think a plug change would make that much difference, but I was so wrong. Its like someone snuck over and put a bigger engine in my Tracker. Can't wait to see if the MPGs stabilize.

Thanks everyone.

David

Sounds exactly like my experience with the change in spark plugs - huge difference!  The old Bosch ones came out sooty like you described.  I put in the NGK's and decided to change them out after 30k just as routine maintenance and they came out looking pretty good still.