Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!

1991 Honda CRX start issue

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1 year 7 months ago #57774 by juergen.scholl
The fuel pump features a check valve in the supply side. Fuel pressure holding while pinching the return line points to a faulty pressure regulator but not to the check valve. Indeed, the check valve proofed just fine as the pressure didn't drop with the return line choked.

You will have to get all injectors cleaned, some of them may be beyond serviceable.

An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
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1 year 7 months ago #57791 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
Newest update dealing with code 6

I bought a new sensor and installed it. I'm still getting code 6. Battery was unhooked when I installed it. I haven't proved it yet to see if I get a reference signal. If I get a reference signal and it still has code 6 I'll be lost because I believe that means the computer sees it plugged in?

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1 year 6 months ago #58205 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
Hello

Newest update

My ECT does not have a full 5V reference. It's at 2.98V. I checked continuity on the wires from sensor to ECU and it's good. So not a broken wire that I know of. I guess the second thing to do would be check the other wire maybe? I plan to buy the ScannerDanner book to help me out a bit as well.

I have some people telling me that the ECU is bad and some telling me the new sensor is bad. I checked 2 other sensors (TPS and MAP) and they have 5v reference. Can someone point me in a direction they are thinking?

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1 year 6 months ago #58219 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue

Do you have 5v or close to it, with the sensor disconnected?

I don't have 5v at the ECU or the sensor. I check all connections in the wire to try and rule out a break. At sensor is 0, first connector is 0 next connector is 0 final connector is 0 and the pin that goes into the ECU is 0. I have a new ECU to verify. I have a concern though. The car fried the first ECU because of the ignitor and now this ECU that came out of a running and driving car has an issue. What kind of checks can I do to make sure there's not a wiring problem in the car destroying the ECUs. These things are rare and not cheap to come by.

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1 year 6 months ago #58222 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
My guess.

Ignitor grounded out causing a huge short. The first ECU was completely fried in this short. Changed to the second ECU that came out of running and driving vehicle with no codes. Put it in this one and got ECT code. Changed ECT and still have the code. Checked 5V reference and that brought us here. I'm just worried I'll destroy another ECU. These are like 350 an ECU. They are also SUPER rare to come by. Manufacturer doesn't make them anymore.

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1 year 6 months ago #58223 by juergen.scholl
Not sure if I got this right....

You got 0 volt on the reference wire with the sensor DISCONNECTED, on the ECU side as well as at the harness connector close to the sensor.

And then you measure 2.98 volts when the sensor is connected? Or when/where/how did you get this ~3 Volt?

An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
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1 year 6 months ago #58224 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
My fault. I'll give a little bit better detail.

Sensor plugged in
One wire reads 2.98v
One wire reads 0v

At ECU terminal with sensor plugged in it reads 0v

Do I need to unplug ECT to test terminal at ECU? Maybe I misunderstood what I read?

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1 year 6 months ago #58229 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue

You don't need to unplug the ECU connector. Just unplug the sensor.
If you have access to a scanner, just look at the ECT parameter. With the sensor unplugged, you should see -40 deg F and you should see a voltage close to 5v on a cold start.

Well here's a good thing for you. I checked voltage at ECU pin. The connector was unplugged from the ECU and I get 5v but when I plug the ECU connector in I have no voltage. Checked continuity between plugs (I have a jumper harness for my swap) there is continuity. When I check resistance I have .4 and when I check resistance between ECT plug and ECU plug I get .4 to .7 ( I have to have pins inside the plug to get a reading)

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1 year 6 months ago #58232 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
I don't have a super fancy meter. It's a Fluke but it only has Ohms. Nothing more. To ensure you understand. The ECU has pins where the connector goes. I checked reference at that pin and had it. When I plugged ECU connector in I lost it.

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1 year 5 months ago #58373 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
I have a fluke 110 plus. I want to preface that with what I'm about to type.

Was testing resistance with wires again from ECU plug to 14 pin connector. Why? Because I found I lost my voltage going to ECT once I plugged that in. Started testing and I found a wire that got a different reading. Blue/yellow has continuity but it's resistance reads 211.5 when I set my meter to MAX setting...all the rest kept saying OL. Possible I have found my issue?

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1 year 5 months ago #58380 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
I understand you want to help. It's possible I am doing what you are asking and not positive.

Back proved ECU wire plug
Found matching color wire in a 14 plug connector (that's the plug that makes me lose voltage) and turn the meter to ohms and change to max then I take the black to the other side of the wire in the female part to the 14 pin connector.

If I understand what you are saying

1. If OL on max that is a good thing?
2. If I get a reading on max that could be a culprit?
3. Am I not supposed to go wire end to wire end?

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1 year 5 months ago #58393 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
I appreciate all your help with this! I'm sorry if I'm coming off as a pain and not understanding. Wiring is a serious pain for me. It's hard to understand it and hard to figure out what to do.

From here my steps are going to be to finish continuity testing (using the beep setting) all 14 wires on the plug that makes me lost voltage. If I get anything from this then I have a break in the wire.

Then I will change to OHMs and go to a ground in the car (battery was relocated to the trunk and makes it very difficult to use it) and touch each wire to see what I get. If at any point I get a reading then that tells me I have a short somewhere.

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1 year 4 months ago #58763 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
Hi everyone. Those that have helped me along I appreciate it so much! I wanted to update you that all codes have been cleared! The car still doesn't start but I'm at a point now that I can troubleshoot this part. I know I'm getting fuel. In fact I'm wondering if I am getting too much fuel so that's one stop. I need to ensure I am getting spark and I will be checking timing as well. It seems like it wants to start just won't.

How did I fix the code 6? Well I changed the entire cabin harness as I found several more wires that looked to be spliced and couldn't figure out where they went. After changing that codes went away.

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1 year 4 months ago #58951 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
Well. Been doing some more testing because I have a crank no start no spark issue now. Here's what I've done

Battery voltage at distributor

Verified resistance is in tolerance on all sensors inside it.

Checked resistance in the coil and resistance is in spec

Voltage in but no voltage out of distributor. I had a test light on the tower of the distributor (tower had a spring out of it) and I was getting nothing out of it but the coil resistance is in spec? Don't understand this.

I have injector pulse on all injectors so the computer is getting signal.

Any thoughts on what I can do here? I have no spark at the plugs.

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1 year 4 months ago #58966 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
Very helpful. Also hope you had a good Thanksgiving.

Ran tests today and I'm really confused. I have spark out of the coil (let's pretend I always had spark out of coil. Rookie mistake).

Did an injector pulse test.
Results
Injector 4 has a pulse
Injector 3 is constant open and no pulse
Injector 2 does nothing
Injector 1 does nothing

That's where I'm lost. How does one injector have pulse but not the rest? I am beginning to think this aftermarket harness that was made has an issue.

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1 year 4 months ago #58974 by Paul P.
Replied by Paul P. on topic 1991 Honda CRX start issue
Monde,

I was reading this thread and decided to look up a wire diagram.

I don't recall ever working on one of these or ever seeing this resistor. It would explain some of the injector power issues.

I wonder if it is a current limiting resistor because these injectors have no zener diode?

Interesting.


Never stop Learning.

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1 year 4 months ago #58977 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
So the car does not have a resistor box. The resistor box is needed for low resistance injectors. Total resistance needs to be around 11 ohms and low resistance injectors are typically 4-5 and then the resistor box helps get them to 11. My injectors are high resistance injectors so they already at 11 ohms. This car is a swap car so it's OBD0 single cam when stock. The swap is to OBD1 DOHC. I believe it has something to do with the way the new harness was wired. When I go battery positive to the control wire on injector 2 with test light the main relay goes in rapid fire mode and on another injector it just clicks. Talked to one guy who specializes in this swap for my gen Honda and he says it's something in the injector wiring. Now I need to figure out what so I can call the company that made my harness and have them fix it.
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1 year 2 months ago #59767 by Jwilusz
Replied by Jwilusz on topic 1991 Honda CRX start issue
To everyone that assisted in this thread. Thank you all for your help! Your guidance and just reading my venting is appreciated. The car is now running and driving!

What happened?
Well I found 45 splices on the interior harness and several wires that simply went to nothing. After installing a new interior harness and a new engine harness I still couldn't get it to start. Upon review of a wiring diagram I found that the plug on the driver side strut tower that connects the injectors from the engine harness to the interior harness was wired for a different model. After de-pin and properly installed the car cranked right up and runs beautifully. What a wiring mess!

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