MthaFuknGreen
Green on the scene.
get a helms manual for your car.
the specs might be in a chilton, but i dont think so.
hunting idle issues.
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get a helms manual for your car.
the specs might be in a chilton, but i dont think so.
hal9000
New Member
I'm selling the car as soon as I get this issue fixed. Really don't want to spend $100 for a Manual (More than avg for me since I have to pay the "small town tax" if I buy it locally). Unless anybody can confirm that the manual contains the sensor range values, It would be wasted money for me. And if somebody could confirm that I don't see why to not share that little tidbit of info.... please?
One other person suggested that the speed sensor or TPS might be different between an auto and manual trans car (remember I swapped transmissios from AT to MT). Anybody know if that's true?
One other person suggested that the speed sensor or TPS might be different between an auto and manual trans car (remember I swapped transmissios from AT to MT). Anybody know if that's true?
The Throttle Body uses a different part# between auto and manual.... not sure of the difference yet plus I just don't see it causing those symptoms though, but who knows?
The speed sensor.... don't really see that making a difference either, but I believe it's in your cluster (speed pulser in wiring diagram).... you changed to a M/T cluster?
There is a ground point for all of the sensors at the thermostat housing. I'd check it. And check again for air @ the coolant bleeder.
edit : only difference I can see/think of on the TB is the auto one has a place for the auto cable. The TB houses the TPS by Honda (only way to get the TPS) and the aftermarket DPFI TPS' are listed the same IIRC.
The speed sensor.... don't really see that making a difference either, but I believe it's in your cluster (speed pulser in wiring diagram).... you changed to a M/T cluster?
There is a ground point for all of the sensors at the thermostat housing. I'd check it. And check again for air @ the coolant bleeder.
edit : only difference I can see/think of on the TB is the auto one has a place for the auto cable. The TB houses the TPS by Honda (only way to get the TPS) and the aftermarket DPFI TPS' are listed the same IIRC.
Last edited:
disableddan
Crazy Insane
From Haynes Manual-
EACV resistance- 8 to 15 ohms
IAT sensor resistance- 1-4k ohms at room temp
MAP sensor voltage- ~5 volts
That's about all I could dig up, hope it helps!
EACV resistance- 8 to 15 ohms
IAT sensor resistance- 1-4k ohms at room temp
MAP sensor voltage- ~5 volts
That's about all I could dig up, hope it helps!
hal9000
New Member
Thanks guys.
I've found a site with good info for the sensor values and a few other things here....
88 - 91 CRX ECU Error Codes
Unfortunately, I won't have time to start checking things again until I get back from Texas (I'm going hog hunting starting tomorrow), so Probably not till the weekend after next at the soonest.
Scott@8, no I didn't swap the cluster, just the transmission and ECU. Can't see why changing the cluster would be important, but like I said, I'm no expert on early Hondas so maybe there's something that I'm unaware of....
Really, I suspect either 1) a bad ecu, or 2) some incompatibility between AT and MT parts, or wiring that I didn't change. I just can't see how parts that worked perfectly in the AT setup would fail during the swap and not work right in the MT setup... The ECU and trans are all that changed... So It's gotta be directly related to that.
Sooo, my next two questions are 1) can anybody confirm what ecu is the factory 5 speed ecu for an '88 CRX DX? (and are they the same for all 88-91, or one year only like some of the other '88 parts?)
And, 2) has anybody else who has done an AT-MT swap confirm what wiring changes you needed to do? All I did was loop the neutral lockout together and re-wire the reverse light switch to from the shifter to the trans. Are there any other wiring differences that I missed?
I've found a site with good info for the sensor values and a few other things here....
88 - 91 CRX ECU Error Codes
Unfortunately, I won't have time to start checking things again until I get back from Texas (I'm going hog hunting starting tomorrow), so Probably not till the weekend after next at the soonest.
Scott@8, no I didn't swap the cluster, just the transmission and ECU. Can't see why changing the cluster would be important, but like I said, I'm no expert on early Hondas so maybe there's something that I'm unaware of....
Really, I suspect either 1) a bad ecu, or 2) some incompatibility between AT and MT parts, or wiring that I didn't change. I just can't see how parts that worked perfectly in the AT setup would fail during the swap and not work right in the MT setup... The ECU and trans are all that changed... So It's gotta be directly related to that.
Sooo, my next two questions are 1) can anybody confirm what ecu is the factory 5 speed ecu for an '88 CRX DX? (and are they the same for all 88-91, or one year only like some of the other '88 parts?)
And, 2) has anybody else who has done an AT-MT swap confirm what wiring changes you needed to do? All I did was loop the neutral lockout together and re-wire the reverse light switch to from the shifter to the trans. Are there any other wiring differences that I missed?
hal9000
New Member
Well, I'm back from my hunting trip (got my pig) and while I don't have much spare time for the car I decided to check out a hunch.
The ECU I have is a 37820-PM5-A080. I'm not 100% sure, but I think that might be the wrong ECU. I found an ebay listing for a 37820-PM5-A060 which is listed as the stock ECU for an '88-91 CRX DX w/ manual trans.
I can't find any break down of ECU's by year/model. Can somebody either direct me to one, or confirm the year/model that my ecu is out of? A wrong ecu would be an easy fix to my problems if thats all it is.....
The ECU I have is a 37820-PM5-A080. I'm not 100% sure, but I think that might be the wrong ECU. I found an ebay listing for a 37820-PM5-A060 which is listed as the stock ECU for an '88-91 CRX DX w/ manual trans.
I can't find any break down of ECU's by year/model. Can somebody either direct me to one, or confirm the year/model that my ecu is out of? A wrong ecu would be an easy fix to my problems if thats all it is.....
MthaFuknGreen
Green on the scene.
the chances of someone swapping the stock ecu from your car to another stock ecu for the wrong engine are very slim.
its probably not the wrong ecu.
they are both pm5 which is all that matters.
i believe the different numbers are just like serial numbers or something.
i thought the same thing cuz the numbers on mine were a little different then one i saw online, so i spent 80 bucks for a new ecu and tcu for nothing.
its probably not the wrong ecu.
they are both pm5 which is all that matters.
i believe the different numbers are just like serial numbers or something.
i thought the same thing cuz the numbers on mine were a little different then one i saw online, so i spent 80 bucks for a new ecu and tcu for nothing.
hal9000
New Member
Well, I did the swap, and I bought the ECU separately from the trans so they came from two different cars.... But you are correct. I just found out how to decipher the ECU numbers.
PM5 are CRX ecus, A080 is for a manual trans. The rest of the code is just the software revision.... I still don't know if different revisions might have different operating parameters or need different sensors, but it's probably the right ecu....
Too bad really, that would have been the easy fix.... I've been fighting this idle issue for a while and not been able to track it down....
Any ideas regarding what would cause the idle to stay high (anywhere between 1100-1700 depending on conditions) unless the throttle is blipped (which drops it down to base idle until the next time the throttle is touched)? I'm pretty much out of ideas.
PM5 are CRX ecus, A080 is for a manual trans. The rest of the code is just the software revision.... I still don't know if different revisions might have different operating parameters or need different sensors, but it's probably the right ecu....
Too bad really, that would have been the easy fix.... I've been fighting this idle issue for a while and not been able to track it down....
Any ideas regarding what would cause the idle to stay high (anywhere between 1100-1700 depending on conditions) unless the throttle is blipped (which drops it down to base idle until the next time the throttle is touched)? I'm pretty much out of ideas.
89' Project Civic
d16a6/d16y8 "mini-me"
An MPFI ECU is the (PM6), whereas the DPFI ECU is the (PM5). Trust me they both work differently. I was running my PM6 on my DPFI and it ran like garbage. I was just experimenting though, you never know, hehe.
89' Project Civic
d16a6/d16y8 "mini-me"
In order to find the PM5 or PM6 E.C.U. codes check the bar code on the side and look in the middle of it, it should say either.
hal9000
New Member
Yup, I already had that part. Thanks though. Since it's a PM5 it sounds like there's no chance that it's the wrong ECU (one more possible diagnosis eliminated at least).
Anyway, I've been out of town all week. Just got back last night, and will be leaving again tomorrow. No time to work on the car, but maybe next week I'll get the chance...... Till then it's just the "armchair mechanic" game for me.
Anyway, I've been out of town all week. Just got back last night, and will be leaving again tomorrow. No time to work on the car, but maybe next week I'll get the chance...... Till then it's just the "armchair mechanic" game for me.
hal9000
New Member
I finally got back to the car for a few minutes today. I decided to focus on the linkage again and found that the throttle isn't returning quite all the way to idle. I can push it closed by hand at the linkage and the idle will return to baseline until I rev the engine again. Neither of the vacuum motors on the side of the TB appear to be holding the throttle open, so unless there's another motor or solenoid that holds the throttle plate which I don't know about, the problem just about has to be the throttle sticking in the last few hundreths of an inch of movement. Little enough that I missed it last time around.
I disassembled and lubricated the linkage, that didn't fix the problem.... So I opened the airbox and lubricated the linkage from the inside where it passes through the throttle body. That didn't fix it either.
My TPS appears to be riveted in place, so I didn't remove it.... Is it possible that it's binding up internally and holding the throttle open (OK< I know it's possible.... Has anybody heard of it happening?) Maybe it's got dirt built up in it or something? I don't want to cut the rivets just to find that it's not the problem.
Also, the idle still hunts by about 50 rpm. I can hear the injector firing for a second, then stopping, then starting, then stopping, as the idle hunts.... Is this normal for a DPFI car?
Thanks all. At least I think I know the problem now. If I can figure out what's binding, I should be able to fix it now....
I disassembled and lubricated the linkage, that didn't fix the problem.... So I opened the airbox and lubricated the linkage from the inside where it passes through the throttle body. That didn't fix it either.
My TPS appears to be riveted in place, so I didn't remove it.... Is it possible that it's binding up internally and holding the throttle open (OK< I know it's possible.... Has anybody heard of it happening?) Maybe it's got dirt built up in it or something? I don't want to cut the rivets just to find that it's not the problem.
Also, the idle still hunts by about 50 rpm. I can hear the injector firing for a second, then stopping, then starting, then stopping, as the idle hunts.... Is this normal for a DPFI car?
Thanks all. At least I think I know the problem now. If I can figure out what's binding, I should be able to fix it now....
hal9000
New Member
Yeah, that was the first thing I checked. The cable has slack at idle, and I've lubed it so it moves freely.
I played around a little bit yesterday, and I'm starting to second guess my diagnosis. I can get the throttle down to base (about 750), shut off the engine, and restart it without touching the throttle, and it'll be back up at 1200-1500. Either something is blipping the throttle at startup and it's not returning, or something is spoofing the ecu and it's changing the mixture causing the idle to go up.... The sticky linkage may not be the problem, or not all of the problem after all.
God this is bugging me. I absolutely hate early generation fuel injection systems. They're just too hard to diagnose.
Anybody want to buy a CRX?
I played around a little bit yesterday, and I'm starting to second guess my diagnosis. I can get the throttle down to base (about 750), shut off the engine, and restart it without touching the throttle, and it'll be back up at 1200-1500. Either something is blipping the throttle at startup and it's not returning, or something is spoofing the ecu and it's changing the mixture causing the idle to go up.... The sticky linkage may not be the problem, or not all of the problem after all.
God this is bugging me. I absolutely hate early generation fuel injection systems. They're just too hard to diagnose.
Anybody want to buy a CRX?
hal9000
New Member
I sooo thought I had the problem solved, but alas! No luck....
This morning I tested the temp sensors, they're both good. When I checked the TPS on an oscilliscope though, it was pretty wacked out near idle. After finding out that nobody in town stocks TPS sensors for this car (???), I tracked down a good used one, tested it to confirm it works, and installed/calibrated it with high hopes that it would solve the problem.... NOPE! No change at all. The idle is still high and erratic.
I think I'm back to either a bad ecu, or a wiring problem (remember, I did an auto to manual swap and ecu swap)...
Can anybody post links or pinout diagrams for an automatic 88 crx dx and a manual 88/89 CRX dx manual? I have looked and haven't been able to find anything that differentiates between the two.... The only differences I know about are the backup light and neutral lockout, and that's all I changed when I did the swap......
This morning I tested the temp sensors, they're both good. When I checked the TPS on an oscilliscope though, it was pretty wacked out near idle. After finding out that nobody in town stocks TPS sensors for this car (???), I tracked down a good used one, tested it to confirm it works, and installed/calibrated it with high hopes that it would solve the problem.... NOPE! No change at all. The idle is still high and erratic.
I think I'm back to either a bad ecu, or a wiring problem (remember, I did an auto to manual swap and ecu swap)...
Can anybody post links or pinout diagrams for an automatic 88 crx dx and a manual 88/89 CRX dx manual? I have looked and haven't been able to find anything that differentiates between the two.... The only differences I know about are the backup light and neutral lockout, and that's all I changed when I did the swap......
89' Project Civic
d16a6/d16y8 "mini-me"
If you need a PM5 ECU I will sell you one for $5 plus shipping. Let me know.
89' Project Civic
d16a6/d16y8 "mini-me"
Any other parts needed for wiring or ECU's let me know as well. I have a PM6 ecu for $10.00 plus shipping.
hal9000
New Member
Thanks for the offer, but I think I'm OK for now. I've got the stock auto ecu still, and from the reading I've been doing, it sounds like that will actually work fine. It'll just throw a code for the auto trans lockup solenoid. If that works then I'll call it done.
If it doesn't work, I'll give some serious thought to grabbing the spare v-tech head my friend has and just getting rid of all the DPFI components by doing a mini me swap (I really don't feel like doing it, but hey, I'll take the extra hp if it solves the problem in the process).
If it doesn't work, I'll give some serious thought to grabbing the spare v-tech head my friend has and just getting rid of all the DPFI components by doing a mini me swap (I really don't feel like doing it, but hey, I'll take the extra hp if it solves the problem in the process).
