Hello all,

I'm new to Rover world, been wanting one for quite some time...I bought an '01 Disco II, 127,000 miles, SE, and I can put the CDL linkage in it. Been working on the little bugs that it has, before it gets the lift and tires, but in the mean time, I had a Magna Flow straight flow though design muff put on, and took off the Resonator. The next day I noticed a hesitation that happens when either you: throttle down to make the rig down shift, or after you leave a stop light and you want to gain some speed, it acts like it has a flat spot just before it shifts, and sometimes not even around a shift? It seems to have lost some low end highway power too. I've been reading all i can find on here, but not exactly finding anyone else thats experienced the same....Do I need to put the resonator back on? More back pressure?

Thanks for any info,
Dan

 

I should also state:
It had recent tune up, wires & plugs
No stored or current codes other than shuttle valve did come up, that was cleared, but still need to repair in the future...
I rebuilt drive shafts
Brakes
Run Premium fuel
Heads and etc been done
I'm currently working on changing all the fluids and trans filter, among other things!

Dan

 

After looking at the resonator and seeing its a straight through design, I opted not to put it back on...Couldnt see what differance it would make. Pulled spark plugs, NGK Iridiums, they were white with yellowish tan electrodes, wires are STI 7mm's that look and feel brand new. I will do a fuel pressure test I suppose next.....

 

I'm just taking a shot in the dark, but check your O2 sensors and your throttle body. Throttle body may need to be cleaned with some carb cleaner. O2 sensors may be going bad, but I'd think they would throw a code if they were.

Honestly, I have no idea how to help, but that was first thing that popped in my mind.

 

I agree...I looked though and around the butterfly and there was decent carbon build up I could see. I will look into cleaning. O2 should throw code I would think also. Thanks for input. It acts exactly like a carburated engine with a Thermoquad or Quadrajet that has a flat/dead spot between the primarys and before the secondaries open. I cant just go out and adjust some linkage on the throttle body!! I will win

 

You need some back pressure for the engine to run properly, to much or not enough back pressure will make it run poorly.
If it was carburated and no sensors at all you could adjust the ignition timing to compensate, but the computer is trying to and the values are to far out of range, eventually you will get a check engine light and burnt up exhaust valves.

 

With having both cats in place....the muffler man said back pressure wouldn't be a problem?? He also stated that the only after market muffler that creates more back pressure in a system, was a FlowMaster...? Not sure if this is true or not. Maybe I will end up with a Flow Master? He put a Magna Flow single chamber on mine (straight through design with fiberglass packing)...I'm probably going to take it to our local Rover mechanic for a trouble shoot appointment this week...I will sure let the forum know what we find out....

 

Go to AutoZone and buy a cheap muffler of the correct type, install it, does the hesitation go away?
My money is on yes.

 

So I took it to the local Rover Indy guy here in town back when I started this thread, and he found 0. I live with the slight hesitation when and if it does it when I down shift.

 

So start a fresh thread in the D2 section, and explain in detail what is going on, what has been checked, and what codes you currently have.