SOHC hesitation and acceleration problem

[mfroelich]

I had the same problem with my DE. My fuel pump was the problem so I replaced it and everything worked fine, you should try that. I know that sounds weird because fuel pumps usually either work or they don't.

[AndyG]

I already replaced it with a walboro.

[AndyG]

Ahhhhhh! Yes I think I fixed it. I was just freaking checking my engine harness and connections and I forgot to plug in the idle switch back in. It is great now except for the high idle unplugging it causes. I just now have to buy a new tps/idle switch unit. I am so happy to find the solution after almost 7 months. Thank you all for your help! It was much appreciated. I now have a reliable strong s13.

[AndyG]

Well.... Spoke too soon. Put on a new auto tps. And nothing... It acted just as before.. Should I try a manual tps?? I still have an auto ecu. This was a 5 speed swap with a 91 transmission. Is there any working I was supposed to do other than the speed sensor??? Please help. It runs fine with the tps and idle switch unplugged except for some bucking and a high idle.

[AndyG]

okay.. got the manual tps. when i plug it and adjust it it has slow revs. when it is unplugged it revs fast please help?

[compactfean]

Set the tps to .45 volts at closed throttle. Make sure the voltage moves up smoothly to 4.xx volts as you open the throttle all the way. If its set just like that leave it alone..... Its not your problem.

[AndyG]

It is set just like that. What would make it have good revs when it is unplugged? Also I forgot to say I tested the fuel pressure under load and it is 42. So idk what's next.

[compactfean]

All that means is the tps is working. Don't drive your car w/o the tps. You can detonate your motor that way. What was the final conclusion with the coil? Also you try anything with your egr? Ive cut a soda can up to the shape of the egr valve and used some silicon to seal it for a block off plate. Pretty quick experiment to see id it is egr valve related. (if you don't have smog checks, you could just leave it blocked off)

[AndyG]

What was the final conclusion with the coil?

The new coil and ngk wires stopped the running rich problem. i now have a strong spark.

Also you try anything with your egr?

Ya i read somewhere that if you lift the plat under the egr valve and your engine dies then you egr is good.

and i dont have smog testing.. is it hard to remove the system?

[compactfean]

Depends on how rusted the tube is that goes to the manifold. Other than that, very easy. Id just block the passage for testing, then if it fixes it buy the block off plate. That test method kind of works but egr valves can leak in so many ways that's not the only way to test them.

[AndyG]

which passage do you block for testing? the one coming from the exaust or the part with the moving plate?

[compactfean]

You'd block off the intake manifold where the egr bolts up. Instead of putting a gasket, use a sheet of aluminum with some silicon and bolt the egr back up (to press it against the manifold). If your egr is leaking in the top or the bottom, this will block the entire system.

[AndyG]

okay sweet. can you just remove it all to clean up the bay a bit and plug the exaust hole? i guess i will try that next. this problem is killing me.

[compactfean]

Yes. There is a write up on here with thread sizes and everything. If your egr had a egt sensor, there is a resistor you use to prevent cel.

[AndyG]

If you feel under the egr and push on the plate the engine should die. what about when you rev. if you feel the plate should it rise?

[peteco]

hi, i have the same problem with my 93 vert, all stock except k and n cone air filter.. very slow to accelerate until it hits 2200rpm then works fine, i have tried disconnecting a few sensors and no change at all. guess i should start with a fuel filter and check the pump. used to idle really rough, but that has cleared up