Cat is clogged...or muffler is clogged...

From: Mike Miller <mwmiller6@ATT.NET>
To: vanagon@GERRY.VANAGON.COM
Sent: Monday, September 26, 2011 3:38 PM
Subject: Re: HELP-- 45 MPH @ WOT ???

O2 sensor? Try pulling the lead and see what happens.

Don't blame me if it blows up.

Mike

On Sep 26, 2011, at 2:26 PM, TJ Hemrick wrote:

> I'm going to throw this out there as I'm still having some trouble and
> perplexing trouble at that.� I've been having some problems getting
> the van
> up to speed and holding speed on the highway.� it starts, runs,
> accelerates
> fine.� It's a little slow after 50 but right at 60 mph (4k), the
> engine just
> stops pulling.� If I give it any more gas, she just winds down.� I
> have to
> back pedal to get it up there and keep it there.� It's a VERY fine
> sweet
> spot and I have NO power at that speed.� People are blowing by me
> like I'm
> going backwards.
> Here's the crazy part, if I floor it, it bogs down and will ONLY do
> 45 mph
> and it has a very slight sputter to it.
>
> Here's the scoop: 87 GL, 2WD, Auto, stock 2.1, I COMPLETELY cleaned
> the fuel
> tank out for a fresh set of gaskets about 6 months ago, new fuel
> filter, new
> fuel pump, new fuel lines from bow to stern (dumped the firewall
> fitting),
> new FI clamps and hoses on the injectors, and has been running well
> (aside
> from marginal gas mileage).
>
> I've been through a few tanks of gas and a bottle of water remover
> so that's
> a non issue.--NO CHANGE.
> I swapped AFM's since it's quick, easy, and I have a few spares. --NO
> CHANGE.
> I swapped Air filters (for the same reason as above). --NO CHANGE.
>
> I've pretty much given up on a fuel flow or air flow issue as it's
> at the
> EXACT same speed/RPM range EVERY time that's plaguing me with the
> slowdown
> and it's ONLY when I dump her to the floor that it goes into the speed
> DECREASE.� It's so counter intuitive to back off the pedal when you're
> trying to pick up speed.� Especially when just one or two
> millimeters too
> much and now you're slowing down due to throttle position and that
> semi is
> right at your back door and closing fast!
>
> I'm going to check the cap and rotor but anyone have any other
> thoughts or
> heard/seen this?
> It's just so strange that it starts and runs fine at all other
> points.� I
> guess I shouldn't completely discount a fuel issue but it's not like
> the new
> pump is cavitating ONLY at that speed and every time ONLY at that
> speed.� I
> guess it could be a total fuel volume issue but how could it be,
> again, only
> at that almost exact same point each and every time?� Seems too
> specific for
> fuel.� Electronics are the only things I know of that can be so
> repetitive
> and exact.� That keeps putting me back at ignition.
>
> Thanks,
>
> TJ
>
> Yes, I have spare ECM's and AFM's so playing swaptronics is not a
> problem.