carlos8

hi guys, I'm working on this stupid low voltage issue at D17 for a while.

The ECU P06 chipped vtec converted. (NEW)
MAP Omni 3 bar.

So I'm getting 3.52v at map sensor plug Pin d17 with engine ground and 4.95v at D19. After check the harness and try other MAP I decide to buy a new ECU, and same thing still happen. The ECT, TPS and MAP power wires get the 5v reference and the car start and idle all day, always you not press the gas when it chokes and die.

I put a direct wire from d17 to MAP and the same 3.52v and chokes. There's another power source for d17, because all is getting 5v less this pin.

Thanks in advance

rick_rabies

so your running boost?
for the time being try an oem map sensor see if thats the problem.
if so. then you need more than a chipped ecu. you need some thing able to edit and calibrate new map and or tps

carlos8

Yes, boosted

Try OEM one with a new program for the injectors and stock MAP and the same thing.

Ho yes this car is running on Ectune, also try with Crome Pro and no changes.

No problem on both programs whit MAP Calibration, the car was running perfect for 4 years.

I just follow the steps from the FSM to diagnose MAP issues, lead me to a bad ECU so I put a new one and the problem still there.

rick_rabies

interesting. have you chased the wires of known problem? maybe cut or shorted?
engine harness and under dash harness

Former User

1. Unplug the MAP sensor.
2. Turn key to ON(II).
3. Individually measure voltage to body/engine ground at each of the three wires in the unplugged connector.
4. Also measure voltage at each of the two outer wires using the central wire as ground.
5. Post the voltage measurements for all 5 tests.

carlos8

Results:

MAP plug to engine ground:
1-Yell/red = 5v
2- grn/wht = 0.01v
3- red/grn = 3.52v

Map plug sg1 as ground:

1- Yell/red = 4.99v
2- red/grn = 3.52v

ECU plug D

D17 + D21 = 3.52v
D19 + D21 = 4.99v

Former User

MAP sensor unplugged? Done by backprobing the connector?

Did you mean D19 + D17?

carlos8

Yes sir, Map unplugged, back proving.

I use conversion harness with obd1 ECU

d17 map signal
d19 map voltage
d21 SG1

Former User

carlos8

should I prove d17 + d19? Never test those two before maybe this is my mistake in diagnosis this.

always I tested the map 17+21 and 19+21

Former User

I'm concerned about your voltage readings. The 17+21 measurement makes sense because 17 is ground and 21 is hot.

However, the 19+21 does not make sense because both those wires are hot. Given that there is 1V difference between the wires, the reading should have been 1V, not 4.99V.

Describe how you do the voltage tests.

carlos8

First I'm fallow this for the pinout.

http://technet.ff-squad.com/wiring.obd1.htm

Set the voltmeter to 20v, Turn switch to ONII, put the black prong in the engine ground and with the red prong with a paper clip adapter test the 3 connectors on the MAP plug disconnected.

On the ECU use the two prongs with clip adapter to back prove with the MAP disconnected.

What I'm lost is in this pinout the D21 pin is SG1 ground, D17 map signal and D19 map power. So according to this d21 is ground and d17 and d19 are hot.

Former User

You are correct. My mistake. D21 is indeed the ground.

Your test results point to the ECU or power/ground to the ECU.

Does battery voltage reach ECU connector pins A25 and B1 with the key in ON(II).

Is there continuity to body ground at A23, A24, A26, and B2 with the key off?

carlos8

Results:

Switch ONII body ground

A25 = 11.88v
B1 = 11.88v

Switch off body ground continuity.

A23 = YES, 006
A24 = YES, 006
A26 = Yes 005
B2 = Yes, 005

Battery voltage engine off = 12.36v

Former User

Everything points to the ECU.

carlos8

You know I can send the ECU back to Advancedignition in Arizona to be checked, since it have a 90 days warranty.

What bother me is the old ECU, test the same results and is right now in one client car working perfectly.

Former User

Same voltage readings installed in client's car?

carlos8

The last one results NO, Because I not perform this test at the time.

But 5v at Map plug and D17 and d19 pins, Yes.

that's why I made this thread looking for something wrong with the car voltage. But apparently it's fine, I'm going to swap Ecu's tomorrow and perform the tests on both cars.

tony_2018

Didn't you say you bought a new ecu? So you swapped ecu's already right?

carlos8

Yes sir, I'm using the new in my car with the same results as the old one.

But the old works great in a client car.

carlos8

Hi, RonJ

The civic I put my old ECU, MAP plug results.

Yell/Red = 5.03v
Red/Grn = 3.60v
Grn/Wht = 0.01v

Plug disconnected, switch to ONII using engine ground, voltmeter set to 20v.

We are using this car testing it and works great.

Former User

So it's now safe to conclude that the lower voltage at the Red/Grn wire is caused by the ECU. However, given that this^ car runs fine, then you should look to other possible causes for your performance problem.

What car and engine? Turbo? Is your setup tuned?

tony_2018

I'm surprise the ecu didn't spit out any codes for high voltage map sensor, unless obd1 ecu's don't have that

carlos8

No Tony, since the car start with this Thing, never pop a CEL. And it's working if I disconnect any sensor the CEL shows up and can retrieve the code.

Yes ronJ, the car is tuned since 2010 and apart from maintenance and a few broken parts the set up still the same. This start breaking in boost after 6k and getting worse every day to the point, that right now you press the gas and it no rev just chokes and die or rev slowly with the wideband completely lean.

Civic Ex 97
Ls VTEC
SC34
9.0:1/Eagle rods
B16 head Supertech valve train, GSR cams
P06 chipped and VTEC (Ectune but also try Crome Pro) no change.

Wdpfreak145

Poor craftsmanship of the ECU conversion harness?