Stumbling Acceleration

[Bullz_EyE]

I just replaced my MHG with a composite one due to coolant seepage into one of the cylinders. When I ran the MHG, for about 25 miles, she felt nice n smooth, despite the HG leak. Now she's running again, but below 3500 RPM she feels like an old dog, she hesitates, stumbles, and stutters, and she dosen't idle as smooth as before. She dosen't feel right at all. I don't understand how she went from feeling smooth to her current condition. She's not throwing any codes, and I can't find a vacuum leak anywhere, she has new NGK Iridiums, NGK wires, new Genuine Toyota Fuel Filter, the timing is set @ 11. :1zhelp: Please.

 

[mrnickleye]

Re-check the timing belt setup. A tooth off can mess you up. Also the dist/cps setup.

 

[Bullz_EyE]

I'll verify the cam timing. Meanwhile, any other input?

 

[mrnickleye]

We just had 2 different cars in today. Misfires. One, the guy had changed his own plugs and wires. A cylinder was not firing. Turned out to be a plug that had got the outer 'ground' electrode banged, and collapsed down onto the center electrode.

The other had bad plugs and wires.

Try idling the car at nite in the very dark, then wiggling the wires a bit and see if you can see any little sparks jumping to metal. Perhaps a wire or 2 is bad. Pull plugs and put in a new set. Keep old ones for spares, if they look good.

Idling, spray some 'brake cleaner' on all the vaccum ports and intake manifold to see if engine rpm changes.

 

[Godspeed]

my new 86.5 na is stumbling real bad and sputtering i put in new plugs and msd wires it has new coil and igniter good gas and good fluids do you think it could be a bad vacuum leak? if i slow push the gas it will get to around 2k and it cuts out and drops to around 600 any ideas i planned on checking the timing also.

 

[johnathan1]

eviltwins: maybe check your tps? sounds like what happened to my car, unplug the tps, and see if that helps!!

 

[Dirgle]

Cracked spark plug porcelain bit me in the ass once. Check the simple stuff first.

 

[Godspeed]

ill check the tps next and i just installed new plugs and inspected them upon installation very good.

 

[Bullz_EyE]

My problem still persists.

 

[aye mate]

Boost leak?

 

[MKIIINA]

did you swap plugs when you did the hg swap? if so the coolant may have fouled the plugs.

 

[Bullz_EyE]

New Iridiums, plugs were not fouled. I don't see any problems with boost leak. It stumbles under light and hard acceleration, on or off boost.

 

[tubbie]

Bypass your fuel pump resisitor, see if that solves the problem.

 

[Bullz_EyE]

Bypass your fuel pump resisitor, see if that solves the problem.

A link or post on this procedure please. Thanx.

 

[Bullz_EyE]

Ok, I figured out the stock bypass valve is long gone. That still dosen't explain why it was smooth before and not now. I still have to replace it. The car starts very easy, even on cold mornings. My car is so close to being smooth it sux. I was thinking my stock 2ndary cat may be clogged, but that wouldn't explain why it was smooth before and not now either. I'll reverify ignition timing when I get the chance, as for cam timing, it is dead on.

I'm still interested in other input, as well as bypassing the fuel pump resistor. From my symptoms, it does seem to be a fuel problem. Puzzled and perplexed. :aigo: :nono: :icon_conf

 

[Bullz_EyE]

I found the answer !!! I was on the verge of a BHG again ! I know this because it just went bye bye about an hour ago. I think either my head or block is warped or a combination.