Car is 94 Del Sol, non VTEC B20B, has P8R-7 head, EM1 5 Speed, and a P75-A01 ECU.

There is no history available, it is as if the car just appeared in my driveway. Engine appears to be a recent build and probably stock. There is not one drop of oil leaking anywhere and the valve gear looks brand new.

The ECU does not have a chip -or- a trouble code light. I opened it to be sure.

SO: No known trouble codes, car runs great except has jerky throttle between idle and 2,000 rpm. At 2,000 rpm if I ease up on the throttle car jerks with the deceleration, and the reverse happens when I apply light throttle. Above 2,000 rpm it runs perfect under all conditions.

My best guess is a MAP or TPS problem.
HERE IS WHERE I NEED ADVICE ON DIAGNOSIS WITHOUT A TROUBLE CODE LIGHT.

I don't know what intake I have. The TPS seems to be non serviceable. Is that possible?

Pictures show intake manifold and TPS. The TPS is slightly blurry, but you can see tiny C-clips in a recessed area, holding it in. Can it be replaced.?

I am looking for guidance from you Honda savvy guys

 

It looks like all the older Honda TPS's use the shear off bolts.

The way people "service" and calibrate their TPS is by using a hacksaw or drill out the bolts etc.

This thread has some pretty decent info if I recall concerning TPS calibration:

https://honda-tech.com/tech-misc-15/...e-tps-2947986/

The difference in the thread I posted is I used a hacksaw to saw a groove into the bolt head and used a flat tip screw driver to unscrew them from the throttle body. If the bolts are seized up people have drilled them out and retapped them, or filed the sides to grab with vice grips etc. I've seen a few methods used to get them out. Another would be drill holes into the bolts and use an easy out.

 

IL4 OEM Replacement TPS

 

TC39; Thanks for the link, it is perfect for my needs.

I just ordered a TPS and a MAP sensor. I'm not thrilled with this method of diagnosis. What do I need to pull trouble codes? A new ECU?

Should I get a chipped ECU?

What did car my intake manifold come from?

 

That's awesome! Saved that link.

Your first hint can come from measuring the throttle body ID. The size in mm of the opening can give a clue. Mind you it will only be a clue not a definitive indication what the intake is from.

More than likely it's the b20b intake manifold that goes with the engine.

I've not done any research on b-series motors so am not sure if there is a head casting stamp list for the b's so you can see if it matches up to the block.

 

Why didn't you do this before buying a new one? Even if you just throw the new one on there, you still need to calibrate it. After you've tested the TPS, we can move onto the MAP.

 

NAR: My project for today is now to calibrate the existing TPS. Thanks.

Do you have any suggestions on what I can do (in the future) to pull codes?
I am willing to buy a different ECU, if necessary. I do not plan any engine mods.

 

Well, if your CEL isn't on, it isn't on. Just make sure it works. Turn your key to ON(II), and it should come on for 2-3 seconds, then turn off. If it doesn't come on, then the bulb is blown or removed. Replace it. From there, you can just jumper the service connector to get blink codes. You can find a how-to in the FAQ sticky.

 

I recently posted about this problem
There are no trouble codes. I replaced the TPS and the voltages are set correctly. I also replaced the MAP sensor. The throttle cable is adjusted to spec.

The throttle is ON or OFF below 2,000 rpm, and it makes it very difficult to drive.

I am looking for suggestions on what to do next.

 

You are allowed only one thread per topic. Related threads merged. Please read the forum Rules sticky.

 

Post all CEL codes that are currently thrown.

Does the engine idle properly?

 

There are no codes.
The engine idles smoothly.

 

Below 2K rpm would be in the idle range. Can you be more specific and detailed?

 

I am decelerating, with light trailing throttle, and when I reach 2,000 rpm it feels like the engine loses all power - as if I removed my foot from the throttle. It creates a dramatic slowing effect on car.
Applying any throttle at that point creates another jerking feeling, as if I had applied too much throttle.

Once the engine is above 2,000 rpm everything seems normal.
At any rpm if I shift into neutral it goes to a smooth, normal idle.

I rechecked the TPS voltages and throttle cable tension, found all correct. The gas pedal hits the floor at the same time the butterfly goes fully open.

I now suspect non stock (hotter) cams or excessive play in the drive train as possible causes. Could I need a different or Chipped ECU?

It has new stiffer motor mounts, so the engine is not moving much, I think.

Ideas for other things to check are very welcome.

 

What output voltage reading does the TPS have at closed throttle?

 

.49 volts.

Ron; thanks for jumping in. I need the help!

 

I just sold the car to kid who will never drive it below 2,000 rpm.
So, cancel the request for help.
I may see the car around and will report if I learn the cause.