'89 CRX HF + D15Z1 troubleshooting...

[MakDiesel]

I recently test drove my project and a few issues arose. She idles fine but when revving in neutral she hesitates/stumbles below 3k and also has severe rev hang (takes several seconds to return to idle speed, stumbles on the way down too). On the road it's similar with heavy hesitation/intermittent power delivery below 3k and sometimes beyond. It feels like she bucks to get up to speed and that translates into the shifter. I understand this engine is gutless below VTEC/lean burn but VTEC engages approx. at 2200 RPM in these cars, and the hesitation lasts beyond that. Below are specs (engine is stock unless otherwise noted):

- P07 ECU (stock for this engine)
- Rywire OBD-0-1 conversion harness w/ resistor box delete and OBD-1 injectors (stock Z1)
- NO CELS
- stock exhaust, no muffler
- used stock 5-wire O2, how do I check voltage w/ a DMM?
- drained fuel tank, fresh 87 octane
- new fuel filter
- new NGK plug wires
- correct spark plugs
- cap, rotor, button look fine
- Cooling fan doesn't work since I deleted A/C but she doesn't overheat w/ the stock HF radiator, toggle switch for hot days
- DIY engine grounding kit
- DIY polyurethane motor/tranny mounts, slightly stiffer than stock
- Timing adjusted to spec
- Correct PCV valve installed

If there's anything else I'll update, Thanks, Mak

[soletek]

I am stoked to see your thread!!! Check out my new thread in How to do it yourself . . . just in today. If you read the paragraph on transmission you may find the answer to your problem. I sure hope so. If you know of any way to use the HF transmission with the VSS please let me know.

[MatHadder]

There should be an ignition timing connector located under the passenger side of the dashboard. It is a 2 pin connector, with wire colors BRN and GRN/WHT. Jumper these two wires to set timing.

Setting timing will probably go a long way towards fixing your hesitation problem.

[MatHadder]

also, my vx has a fairly bad low throttle hesitation. I think it is related to it coming out of the lean burn mode, but I am not sure. It got a lot better after setting the timing, but it is still there. I am in the process of getting a new fuel filter, and having some injectors cleaned and flow tested. I am hoping this will eliminate the hesitation, but it seems like this is a problem that I hear about with the vx a lot, so it might just be the nature of the motor.

[GasSavers_bobski]

Originally Posted by MatHadder

There should be an ignition timing connector located under the passenger side of the dashboard.

Actually, '88-89 models have the service connector by the driver's side engine mount.

Mak, how can you tell you don't have any CELs if you haven't jumped the service connector?

[MatHadder]

Originally Posted by bobski

Actually, '88-89 models have the service connector by the driver's side engine mount.

Good call. I could vaugely remember that there was something different between the different crx years, but all I had to look at was a 1991 civic manual.

When he says he doesn't have any CELs, he probably just means the light isn't on. It is true though, that he probably needs to jumper the connector and see if there are any codes that wouldnt trigger a check engine light.

[MakDiesel]

When he says he doesn't have any CELs, he probably just means the light isn't on. It is true though, that he probably needs to jumper the connector and see if there are any codes that wouldnt trigger a check engine light.

True, I don't have a steady CEL. Also, when I swapped the Rywire harness in, the instructions indicate which wire does what. At the very end they indicate the blue wire that is on the custom pigtail portion of the harness to be grounded to check for codes. Since I didn't have a CEL and was skeptical I had everything wired correctly having never done a swap before, I intentionally unplugged the VTEC pressure switch and ran the car at idle. The CEL popped up, I grounded the blue wire, and sure enough code 22 flashed (VTEC psi switch error). This new blue wire is now my service connector, as per Paul of Rywire informed me. Mak

[MakDiesel]

***UPDATE 3/22***

After 10 hours today, changed the timing belt, water pump, tensioner and spring (All Honda Genuine parts) and even set valve lash while I was there. Got the crank/cam/ignition timing spot on, but the problem still exists, but the rev pickup is improved. When in fast idle the car is possessed, it surges and falls, fluctuates, etc but ultimately stays above 1.5-2k. After it warms up, the idle settles to 7-800 rpm and it purrs like a walrus (kitten + no muffler). What gives? Also, throttle input on both cold and warm idle causes random events such as rev hang, rough idle, and when cold, surging. Guess I'm not out of the woods yet on this Z1...could it be a MAP or TPS? EGR? Other acronyms? HELP! Mak

[GasSavers_bobski]

- Clean the IACV. Spray carb cleaner down the inlet port in the throttle body until the engine stalls. Let it soak for 15 mins and restart it. Spray 5-10 bursts of cleaner down the port so the engine bogs down but doesn't stall. Repeat until you feel satisfied that it's clean, you run out of carb cleaner, or the fumes get to you.

- Check for vacuum leaks. Spray carb cleaner on various hoses, seals and such in the engine bay, listening for changes in the idle (bogging, stuttering and such). Try pinching off each vacuum hose one at a time at the manifold... If the idle drops, that hose or component is leaking.

- Check the TPS. Pick up a digital multi-meter if you don't already have one. A model with a bar graph helps. Scrape enough insulation off the grn/wht (green with a white stripe) and red/blu wires to make a good electrical connection with the meter. Switch the ignition on and measure the voltage across the wires (grn/wht negative, red/blu positive). You should see between .45 and .5 volts with the throttle closed, and around 4.5 volts with it fully open. You should see a smooth (no voltage spikes - this is where the bar graph comes in handy) transition between the two as you slowly open and close the throttle.

- Unbolt the EGR valve and see if the ports look clogged or the valve looks worn or damaged. If you have a vacuum pump, check that the valve moves smoothly and isn't leaking. Go ahead and soak the ports down with carb cleaner while you're in there.

- Hit it with a brick.

[MakDiesel]

Thanks bobski, I'll attempt them all next week. I have a standard Digital MM, no graphs. I also searched similar complaints and will attempt to test my fuel pump and distributor igniter, but I'll go easiest ---> difficult and see what happens. Thanks, Mak

P.S. Before I try the brick method, I'll get a short video of the idle in action because diagnosing cars using text is difficult.