Civic hesitation problem...

Buddy of mine just rebuilt (with all OEM parts!) a D16A6 with PGM-FI for
his '89 Civic (including the appropriate computer and wiring harness).
Got it installed, turned the key, engine turned 3 times... and fired
right up. Very nice. Idles smoooooth and quiet...

But when he gives it any gas, even just sitting in neutral, it bogs and
hesitates. Hit the gas too fast, and it just sputters and dies. Do it
carefully, and once it gets 1800rpm or so, it works fine. It also seems
to idle a little bit rich.

Thoughts? Ideas? He's checked for error codes, but it's not giving any.

TIA

 

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.
http://www2.moltenimage.com/civic/

 

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.
http://www2.moltenimage.com/civic/

 

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.

 

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.

 

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.

 

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

 

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

 

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

 

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.

 

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.

 

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'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.