Differences between 2 of my SR-5's engine characteristics (Questions)

[jasonaries]

When compairing two of my SR-5's against each other, I find that one just really runs better than the other. I've noticed a couple differences:

The gold car has some hesitation, like there's a fuel flow problem. My mechanic pal doesn't notice it, my mustang driver pal doesn't notice it, but my wife, who has driven both cars quite a bit DOES notice it - so it's subtle. With an upper engine overhaul done in 2001, I'm left to think this might be a corroded fuel line junction problem or something. I seriously do NOT think it's the timing or carb. Any ideas?

Then, the blue car, which runs like it's mint, (unless I'm REALLY out in left field and hallucinating) makes a poppling sound sometimes when I downshift, and the gold car NEVER does. What does this tell you about the settings/tuning between the engines?

Thanks in advance.

[GRiDRaceTech]

Does the gold car have a recent fuel filter? I'm thinking the hesitation could be due to a partially clogged filter.

The poppling sound seems like it's just a difference in fuel mixture or exhaust system condition.

[jasonaries]

fuel filter - check

difference in fuel/air mixture: I'll add that to my list of things to compare.

[TireFrier]

when is the hesitation? upon WOT? partial acceleration? half throttle? it could be the accelerator pump... clogged jets... etc etc. maybe slightly too rich? oh and typically popping from carb is lean and from exaust is rich, but exaust popping can also be caused by an exaust leak, however slight it may be. so i'd get that checked out too.

[jasonaries]

The blue car has always popped, with and without exhaust leaks. So, popping from carb is lean, popping from exhaust is rich, eh? Interesting.

Hesitation on the gold car is right at the "step" that I feel in the throttle cable: there's a point on all my SR-5's where there is a slight change in the resistance when pressing the accelerator. I think it's about 60 - 70% throttle. So, I just end up flooring it all the time - the hesitation isn't present at full throttle.

Now, I'm wondering if the gold car's mixture is too lean. That would make sense. I'm thinking that the blue car was last tuned in the dead of winter when a richer mixture would have been called for in the bitter cold, dense air. The gold car, conversely, may have been last tuned on a hot, humid day. That may be the difference.

Thanks a million for the heads up on which popping is rich or lean. Despite trying to learn as much as I can about auto mechanics, that little detail skimmed past me...

[TireFrier]

remember that popping/backfires aren't always because of a rich or lean condition. ALSO timing has ALOT to do with it. too retarded it pops out the carb. too advanced it pops out the exaust. make sure to check the timing on both vehicles. retarded timing will make your car hesitate when pressing the gas. maybe try cleaning the jets in yoru carb.

[LucidStrife]

KISS = Keep It Simple Stupid

No offence about the stupid part just part of the saying. I am leaning toward the advice given to you by the other posters, but if that doesnt work check the accelarator cable on the car with the hesitation. Make sure its not slightly slack to where you would think it is giving you hesitation, when in actuality it could just be an illusion, because you have to push the pedal farther before it engauges.

Lucidstrife

[jasonaries]

Got it: will focus on checking the throttle cable and mixture on the gold car.

Just a reminder, the blue car pops and runs superbly. It's timing is sweet. Heck, if I could make the gold car run that good and pop, it'd be a no brainer.

Now, I just gotta eck out a sliver of time to fiddle with the gold car. Darn it, I'm wicked busy these days.... thanks for the tips.