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If I may ask, how are you able to get P codes from your 94 civic?
If your car is the stock engine, typically those sensors are not known as factory serviceable parts of the distributor.
so replacing the distributor would be the way to go then. OK just wanted to confirm that.
my buddy has a shop and pulled codes from it, don't ask me either otherwise i would've done it myself!
next time i talk to him ill ask and letcha know.
Also check the mechanical timing. The timing belt may have skipped one tooth.
Maybe you have a 96-00 Civic?
it is def a 94 civic! how would i be able to tell if it skipped a tooth? forgot to mention there was tons of oil in the distributor cap. so i had that replaced but not the rotor. it was working fine for a little bit then back to limp mode after a day or so. really unfortunate so im willing to bet its the distributor!
if i hit past 2k rpm it backfires and loses power.
The codes make sense ONLY if your car has an OBD2 ECU, which is highly unlikely. Your buddy may have mistakenly given you codes from an OBD2 car in his shop. Until you sort this out, it doesn't make sense to chase OBD2 codes for an OBD1 car.
You don't need your shop buddy to pull CEL codes from the ECU. Just jump the service connector and watch the CEL blink the codes.
The codes make sense ONLY if your car has an OBD2 ECU, which is highly unlikely. Your buddy may have mistakenly given you codes from an OBD2 car in his shop. Until you sort this out, it doesn't make sense to chase OBD2 codes for an OBD1 car.
You don't need your shop buddy to pull CEL codes from the ECU. Just jump the service connector and watch the CEL blink the codes.
JRCivic1 pointed out that there is some expensive equipment that some shops have that can read Honda OBD1 3 pin diagnostic port. I suspect those machines report in OBD2 code lingo and would provide "P": codes.
But as muellersfan mentioned, you don't need those thousands of dollars machinery, you can just jumper the 2 pin service connector and read the blink codes. Which should still point to the TDC/CYP and CKP sensors all residing in the distributor. If it's leaking oil into the dizzy that can definitely interfere with the running of the car.
JRCivic1 pointed out that there is some expensive equipment that some shops have that can read Honda OBD1 3 pin diagnostic port. I suspect those machines report in OBD2 code lingo and would provide "P": codes.
I found an Innova Scanner that reads OBD2 codes and OBD1 codes, including for Hondas. To read OBD1 codes, it connects to the 3-pin connector, as you would expect. Looking through the manual (below), the Honda OBD1 codes are the format that you are familiar with (see page 115), not the OBD2 PXXXX format.
I found an Innova Scanner that reads OBD2 codes and OBD1 codes, including for Hondas. To read OBD1 codes, it connects to the 3-pin connector, as you would expect. Looking through the manual (below), the Honda OBD1 codes are the format that you are familiar with (see page 115), not the OBD2 PXXXX format.
That's very nice. That would be a more consumer level scanner unlike the systems JRCivic1 mentioned. That is one of the first I've seen that have incorporated the OBD1 systems being they were all different for each manufacturer even more so than OBD2.
I was just looking at Hondash as that was the only one I was aware of that utilized the 3 pin Honda diagnostic port. It's nice to see others are starting to accommodate. Of course, the cars are 25 years old so it's a little late in my opinion but it's also the trend to "self diagnose" before hitting the mechanic. Sales probably finally justify it?
That's very nice. That would be a more consumer level scanner unlike the systems JRCivic1 mentioned.
I presented the consumer-level OBD1 scanner to make a larger point. This OBD1 scanner delivers standard Honda OBD1 codes because that is all that you can get from an OBD1 ECU. An OBD1 ECU lacks the capacity to report more advanced OBD2 codes. Let me use one example to make this point:
-The Honda OBD1 ECU reports a problem with the idle control system by throwing OBD1 code 14. However, OBD1 code 14 does not tell you whether the problem is electrical or mechanical.
-By contrast, when connected to an OBD2 code reader, the Honda OBD2 ECU is able to report two different types of idle control system problems, electrical or mechanical, using two separate OBD2 codes (PXXXX format). However, if you instead jump the service connector of your OBD2 Honda to retrieve the OBD1 equivalents of these codes, the CEL will report only OBD1 code 14, regardless of whether the electrical or mechanical OBD2 code is thrown.
The Honda OBD1 system is too primitive to report more advanced OBD2 codes, whereas the Honda OBD2 system can report both OBD1 and OBD2 codes.
The primary utility of the 3-pin OBD1 connector is to read live sensor data not to obtain more advanced trouble codes.
Last edited by muellersfan; Feb 14, 2020 at 08:51 AM.
I presented the consumer-level OBD1 scanner to make a larger point. This OBD1 scanner delivers standard Honda OBD1 codes because that is all that you can get from an OBD1 ECU. An OBD1 ECU lacks the capacity to report more advanced OBD2 codes. Let me use one example to make this point:
-The Honda OBD1 ECU reports a problem with the idle control system by throwing OBD1 code 14. However, OBD1 code 14 does not tell you whether the problem is electrical or mechanical.
-By contrast, when connected to an OBD2 code reader, the Honda OBD2 ECU is able to report two different types idle control system problems, electrical or mechanical, using two separate OBD2 codes (PXXXX format). However, if you instead jump the service connector of your OBD2 Honda to retrieve the OBD1 equivalents of these codes, the CEL will report only OBD1 code 14, regardless of whether the electrical or mechanical OBD2 code is thrown.
The Honda OBD1 system is too primitive to report more advanced OBD2 codes, whereas the Honda OBD2 system can report both OBD1 and OBD2 codes.
The primary utility of the 3-pin OBD1 connector is to read live sensor data not to obtain more advanced trouble codes.
Thank you for the clarity. That definitely puts a damper on my theory of the machine makers "translating" the OBD1 DTC to an equivalent P code. It also explains why the troubleshooting is far less intuitive when you have things like idle surge on an OBD1 system versus the OBD2 system.
I will add to your last statement. I do believe the other use of the 3 pin OBD1 connector (for Honda at least) was to be able to program the ECU. Or that was the impression I received during my research on the Honda Interface Module (HIM) and the subscription software, of which has evolved to become the Honda Diagnostic System (HDS) and subscription software.
So that still begs the question where the P codes came from for an OBD1 vehicle and ECU assuming it's still OBD1 in the 94. We will have to wait and see what information OP provides after talking to his buddy at buddy's shop.
Thank you for the clarity. That definitely puts a damper on my theory of the machine makers "translating" the OBD1 DTC to an equivalent P code. It also explains why the troubleshooting is far less intuitive when you have things like idle surge on an OBD1 system versus the OBD2 system.
I will add to your last statement. I do believe the other use of the 3 pin OBD1 connector (for Honda at least) was to be able to program the ECU. Or that was the impression I received during my research on the Honda Interface Module (HIM) and the subscription software, of which has evolved to become the Honda Diagnostic System (HDS) and subscription software.
So that still begs the question where the P codes came from for an OBD1 vehicle and ECU assuming it's still OBD1 in the 94. We will have to wait and see what information OP provides after talking to his buddy at buddy's shop.
The HDS can only program ECU's that are of the family of flashable versions... which for sure began in 2006, and there may be earlier examples. '92-00 Civic ECU's are NOT flashable, so the HDS can do nothing as far as programming is concerned with these versions. The original 27C256 location on the ECU board is actually present for the factory to be able to "update" the ECU if necessary. There are ECU's out in the market that have factory added "chips" to replace the original programming in the primary chip. The three that I have seen over the years had 28-pin chips soldered directly to the board (no socket), and the chips had a round UV window in the middle for clearing the memory which was covered by a metallic orange rectangular sticker to eliminate the possibility of memory loss from light exposure.
The HDS can only program ECU's that are of the family of flashable versions... which for sure began in 2006, and there may be earlier examples. '92-00 Civic ECU's are NOT flashable, so the HDS can do nothing as far as programming is concerned with these versions. The original 27C256 location on the ECU board is actually present for the factory to be able to "update" the ECU if necessary. There are ECU's out in the market that have factory added "chips" to replace the original programming in the primary chip. The three that I have seen over the years had 28-pin chips soldered directly to the board (no socket), and the chips had a round UV window in the middle for clearing the memory which was covered by a metallic orange rectangular sticker to eliminate the possibility of memory loss from light exposure.
Thank you for that.
I guess I misunderstood what I was reading when I was researching several years back regarding OBD1.
Last edited by TomCat39; Feb 14, 2020 at 10:05 PM.
Reason: removing hijacking side commentary
There’s a picture somewhere on this site with the early tool that Honda dealers used for obd1. Unfortunately, I couldn’t tell you where it was or if was destroyed by photobucket.
alrighty put the new dizzy in along with a new wireset and still running terribly; probably worse than before and still isn’t revving past the 2k mark. jumped the service connectors and got code 8. would the next best thing be to check the timing; or the wires?
alrighty put the new dizzy in along with a new wireset and still running terribly; probably worse than before and still isn’t revving past the 2k mark. jumped the service connectors and got code 8. would the next best thing be to check the timing; or the wires?
How comfortable are you with tracing wires etc?
Also, is the dizzy brand new oem, brand new after market or some used dizzy?
This might help you check your wiring from the dizzy to the ECU. You may have to google the location of some of the connectors. Taking a quick peek, it looks like distributor to shock tower to ecu.
Left Tower
C101
Tower Harness
4 pin Grey
C102
Tower Harness
10 pin Grey
C103
Tower Harness
14 pin Grey
C129 (VX)
Tower Harness
6 pin Grey
Right Tower
C124
Tower Harness
2 pin Grey
(Power)
C125
Engine Harness
8 pin Grey
Junction
C126
Tower Harness
14 pin Grey
C108
Coolant Temp send unit
C109
ECT
2 pin Grey
C111
O2
4 pin Grey
All but VX
C111
O2
8 pin Grey
VX
C117
EVAP
2 pin Grey
C112
VSS
3 pin Grey
C114
TPS
3 pin Grey
C115
IACV
2 pin Grey
C116
IAT
2 pin White
C106
Distributor
2 pin Grey
Ign Coil
C107
Distributor
8 pin Grey
TDC/CKP/CYP
C104
Starter Solenoid
1 pin Black
C119
Alternator
4 pin Green
C127
Vtec Solenoid
1 pin Grey
VX/EX/Si
C128
Vtec Pressure
2 pin Green
VX/EX/Si
C130
EGR Lift Sensor
3 pin Grey
VX
C113
MAP
3 pin Grey
CX/VX/EX/Si (CDM EX-V)
C201
MAP
3 pin Grey
DX/LX (93 Firewall)
C404
ECM
26 pin Grey
C405
ECM
16 pin Grey
C406
ECM
22 pin Grey
C120
Injector 1 (A1)
2 pin Grey
C121
Injector 2 (A3)
2 pin Grey
C122
Injector 3 (A4)
2 pin Grey
C123
Injector 4 (A2)
2 pin Grey
C118
Oil Pressure Switch
1 pin Black
C110
MT Backup Lght Switch
2 pin Grey
C110
AT Lock up Solenoid
2 pin Grey
Non VX
Label
Wire Colors
Route/Connections
C101-1
ECU Injectors
Red
C404-2 Red ECU A3 to C121-1 Red Injector 2
C101-2
ECU Injectors
Brn
C404-1 Brn ECU A1 to C120-1 Brn Injector 1
C101-3
ECU Injectors
Yel
C404-14 Yel ECU A2 to C123-1 Yel Injector 4
C101-4
ECU Injectors
Lt Blu
C404-3 Lt Blu ECU A5 to C122-1 Lt Blu Injector 3
C102-1
Ground ECU/G101
Brn/Blk
C405-9 Brn/Blk ECU B2 to G101 Brn/Blk
C102-2
O2 Sensor
Wht
C406-18 Wht ECU D14 O2 Input to C111-1 Wht O2 Signal
C102-3
Ground ECU/G101
Blk/Red
C404-26 Blk/Red ECU A26 Ground to G101 Blk/Red
C102-4
ECU CYP/Distributor
Orn
C405-6 Orn ECU CYP B11 to C107-4 Orn Distributor CYP
C102-5
ECU CYP/Distributor
Wht
C405-14 Wht ECU CYP B12 to C107-8 Wht Distributor CYP
C102-6
ECU TDC/Distributor
Orn/Blu
C405-7 Orn/Blu ECU TDC B13 to C107-3 Orn/Blu
C102-7
ECU TDC/Distributor
Wht/Blu
C405-15 Wht/Blu ECU TDC B14 to C107-7 Wht/Blu
C102-8
ECU CKP/Distributor
Blu/Grn
C405-8 Blu/Grn ECU CKP B15 to C107-2 Blu/Grn
C102-9
ECU CKP/Distributor
Blu/Yel
C405-16 Blu/Yel ECU CKP B16 to C107-6 Blu/Yel
C102-10
C103-1
C103-2
O2 ECU ground
Orn/Blk
C111-4 Orn/Blk O2 Heater to C404-16 Orn/Blk ECU A6 Heater control (ground)
alrighty put the new dizzy in along with a new wireset and still running terribly; probably worse than before and still isn’t revving past the 2k mark. jumped the service connectors and got code 8. would the next best thing be to check the timing; or the wires?
If you clear codes from the ECU and install the original dizzy, is only code 8 still thrown?
Do you see where I'm going?
Last edited by muellersfan; Feb 15, 2020 at 04:24 PM.
C107 is the connector at the Dizzy.
C102 is the connector on the passenger side shock tower.
C405 is the plug at the ECU known as the B plug.
Corrosion, broken wire, low continuity )High resistance_, etc.
These are the things that should be checked.
Unfortunately I do not know anything about the ECU to know what components on the PCB affect the distributor signals.
Swapping a known good ECU would be another test of mine.
Re: 1994 Honda Civic limp mode
