Civic hesitation problem...

BTW, it looks real nice, he's done a lot of work cleaning up the body, detailing the interior, and cleaned and repainted all the engine parts.

Matt Ion wrote in news:NE21i.173204$DE1.115546@pd7urf2no:

Does he have enough fuel pressure to run the fuel injection? That takes more pressure than a carbureted engine,and the fuel pump may be different for a carbureted model.

The old engine was a D15, if memory serves, but it definitely had PGM-FI. It runs great past 2000rpm and on up to redline, it's just that initial low-RPM push that's dropping out.

Matt Ion wrote in news:_Y51i.176043$6m4.108395@pd7urf1no:

maybe a bad throttle position sensor? Maybe it's defective at the low end,perhaps a dirty/worn resistive element.

it sounds like you converted from DPFI to MPFI, in which case a bit of wiring was involved

simple run down to check your wiring against

ECU pin component a1 inj 1 a3 inj 2 a5 inj 3 a7 inj 4 a15 inj resistor box

run all red/blk wires from injectors back to resistor box swap pins from c1 and c2 to b10 and b12 respectively run new wire from c1 and c2 into engine bay swap out old DPFI distributor plug to MPFI plug (matching colors) wire from c1 goes to blue/grn wire on new distributor plug wire from c2 goes to yell/grn wire on new distributor plug extend TPS plug 6" and swap outer 2 wires

sounds like you forgot to switch the TPS wires

I thought of that... we haven't had a chance to check it yet, but I'll pass that on the suggestion. But wouldn't the computer be throwing error codes in that case?

Fortunately he still has the old engine, complete with intake, so there's at least a known working one there :)

Both engines (the one that came out of the car, and the new one) have the same intake systems, the "PGM-FI PROGRAMMED FUEL INJECTION" throttle bodies and multipoint injectors. I'll tell him to double-check the wiring, but I don't think that'll be it.

good thinking.

if not, check the cam timing.

it's likely that it is - the tps sensor rotation is opposite on the 2pfi to the 4pfi. the plug and sensors are the same but the wires are reversed as a result.

it may only throw codes if there's a bad connection - like if the slider's worn on the carbon track inside the sensor. reverse wiring won't be a bad connection.

Just a thought...Some of these systems take a bit of time for the various processors to synch and get a baseline established. I don't know about the Honda Civic but I do know that the Chrysler takes a day or so to get completely normal.

DaveD

Except that both the previous engine and the new engine are both MPFI with identical throttle bodies...

Yeah, don't think that's an issue in an '89 with OBD-0.

It would really help to separate mixture trouble from ignition trouble. How about a timing light to see what the timing does when the throttle is opened a bit? The timing should advance a few degrees, but not jump fifteen degrees or retard a lot. (It may retard some based on the rise in MAP.) Similarly he can try adding a squirt of starting fluid into the air cleaner a second before he opens the throttle to see if that improves the response - which would point to a lean mixture on throttle opening.

Mike

then check the cam timing.

Ignition timing has already been checked, but I'll pass on the other suggestion.