Jeff C. dropped his B20VTEC into his CRX this weekend. It fires up and idles alright but has a few problems:

1. With the car in neutral, you can hold the RPM steady all the way up to about 2300. Past that it will hesitate, the rpms will drop to ~700, return to where they should be, drop to 700 and keep doing that until you lift off the gas. It does the same thing in gear, making it very difficult to drive. Going by that B16 vacuum diagram that's floating around, we think we have the MAP sensor and all the vacuum lines hooked up right..maybe not though. What would cause this hesitation?

2. The one time it's been driven so far was under very light load, light throttle, and the rpm never surpassed ~2300. The Autometer A/F gauge (I know, I know) never left the red though. This could be normal, but after putting several thousand dollars into a motor, one tends to become very paranoid. Should this be a concern as long as it's happening under light throttle/load and low RPM?

Some of this info may be irrelevent but here's the specs on the car: 89 CRX Si, B20 block, 1st gen B16 head, JE 10.5s, Eagle rods, ITR cams, Portflow and ITR valve springs, a chipped P28 ECU running an OBD1 DOHC Mugen program, 94 GSR injectors, all OBD1 electronics, 50psi static fuel pressure.

Any and all help is greatly appreciated.



[Modified by 91CivicSi, 9:38 PM 9/15/2002]

 

If your worried about not having your vacume lines connected to the map sensor properly , disconnect all the vacume lines from the intake manifold(except the one that goes to the fpr) and only connect a line from the map to the manifold. plug any open ones on the manuifold and start the car. Also if you had the tps sensor off make sure you guys set it to the proper voltage.

 

TPS and MAP sensor plugs reveresed?

need to re-calibrate TPS sensor?

any codes?

t..

 

Nope, no codes. Anything's possible..how do you recalibrate the TPS?

TIA.

 

ign. on.

test it with a digital volt meter.

check htat the signal from TPS is at or below 0.45 - 0.50v when throttle is closed. (must NOT be above 0.50v!)

and that signal is 4.5v when throttle is fully open.

dunno which of the three pins on the TPS is signal but one is ground, one is +5v feed and other is signal output. (you should be able to work it out)

HTH,

t..

 

well i moved the heated o2 to the back of the exhaust mani downpipe and it seemed to help. i dont know if this was a coincidence or what but it runs better. it idles at about 2k though but i might have traced the prob to the iacv. ill have to play around with the iacv a lil more.
i need to do something about getting a little more fuel. it seems like the gsr injectors are a tad too small.

 

sorry, have to ask - it the TPS OK? still no codes?

how are you setting the fuel pressure?

is it still running lean?

t..

 

tps checked out ok. i was going to also check and see of there was a short between the ecu and tps but i did not get a chance.

i was looking at diagnosing the iacv in the helms and it says something basiclly to this effect...
If car is idling too high, put your finger over the upper port just inside the throttle body. If the idle drops, then replace the IAC.
sure enough, my idle dropped considerable so the iacv may be my culprit.

i have had the fuel pressure anywhere from 60 to 45 w/ my b&m fpr.

judging by the a/f guage the car was running lean, but it said the car was running lean even after i put in a set of dsm 450's. i know the car was definately running rich with those 450's cause i could smell the gas and the plugs were black so i am not so sure about that guage. however, i did forget to plug the resistor box back in , not sure if that would have made a big diff or not.

i am planning on buying that SMC that zip was advertising and turning down those 450's.

 

i found my prob, it was merely a big vacuum leak. turns out, i had only hand tightened my direct port plumbing. the car runs great so far and pulls pretty hard. i have only revved it to 5k so far though.

 

take it easy, then when she's ready go hard

t..