As per my other thread, I've recently replaced the alternator on my 2001 wrx bugeye wagon, when doing this I disconnected the battery to be on the safe side
When I took the car out to make sure everything was ok I noticed that it was running a little off key, similar to if you have a plug starting to break down or a very slight fuel starvation problem, only really shows itself around the 4K rev mark, just very flat.
Since buying the car a couple of months ago I've run it on normal octane unleaded, ( the nearest garage for anything stronger is a fair trip from us ), and it's been fine up until the alternator change.
Anyway, I decided to make the trip and get some texaco supreme unleaded, I think it's about 97 Ron, this seems to have improved things quite a bit.
Does this make any sense to you guys.

 

Battery been disconected mab its put ecu into learn mode again.the alternator rating is it the correct one ?(mightbe overcharging )

 

U might try a good octane booster like the one Andy Forrest recommends,have searched forums on boosters and this apparently is the best out there.black bottle street version.

 

removing the battery on a Bugeye makes no difference, its not like a older classic that does reset the memory in the ecu,
are you sure you havent caught the little hose on the FPR when you changed the alternator, your in that sort of area and its not got a clamp or anything on the hose.

 

I take it that's the small hose that goes into the manifold, it all looks good and I've checked around the other hoses for leaks/splits etc.
Just strange as to why it done it and then got better with higher octane fuel.

 

Right, have now decided its still not right, so where do I start looking, is there anything particular with scoobys that might cause such a thing, or is it like any other car, just start with the simplest and go from there.
With the car just sat there, no load, I can rev right through without any hesitation, so it's showing up under load, this should rule out plugs and leads etc. shouldn't it?

 

nope, could be gap too big on plugs, its Not under load on your drive.

 

Fair comment, that's where I'll start.

 

Plugs checked and re-gapped to .7, what a lovely little job that is, they all looked nice and clean and as if they've been firing ok.
Still not running 100%, is it time to get a diagnostic done on it to see if anything is logged, maybe a coil breaking down under load, or are there other things to check first.

 

Have just been out in the car and decided to try and narrow it down as to exactly what's happening.
From a stand still in first it will rev nicely all the way up to 4.5-5K revs, change to second and keep the revs no lower than 4K it will still pull smoothly, same in 3rd and 4th, didn't get to 5th as road came to an end.
Now, if I do the same as above but let the revs die down to 3.5-4K this is when the problem starts, it just doesn't feel as smooth, especially 3rd gear onwards.
It just seems that it doesn't like that 3.5-4.5K range.

 

bottom ends gone

 

Please explain in a bit more depth how you reach this conclusion.

 

Still not happy with the car, although unless you are driving and know what to look for its only slight hesitation, seeing as all this happened after I changed the alternator could it possibly be something to do with the problem.
It's certainly charging ok, 14.4v when running.

 

Three letters, "MAF" it was filthy, one cotton bud and a drop of electrical cleaner later and the car is running as it should.
So glad it wasn't those, "bottom ends" gone.

 

weird it started just after you had swapped the alternator though

 

I'm not convinced disconnecting the battery does nothing on new ages.

When my 2003 wrx was mapped for part E85, I occasionally got stranded without E85 etc and had to fill up with vpower, and the car sometimes went into base boost mode. The only way to clear it from base boost was to disconnect the battery for a few minutes.

No CEL's etc, just wouldn't boost even after filling up with the correct fuel until battery the battery was disconnected.

 

Exactly why it was confusing me as to what it could be, in the end the engine management light come on and stayed on, plugged it into a code reader to see what was logged and nothing showed up, so just reset history anyway and light went out.
I'd already cleaned the maf, so I knew it was ok, was just curious to see what was logged.