#1 injector troubles

Reply Subscribe

Thread Tools

Search this Thread

Jul 15, 2014 | 08:29 AM

sWcCuZ

Thread Starter

Teching In

Joined: Feb 2014

Posts: 24

Likes: 0

From: Southeast Texas

#1 injector troubles

Recently the car started dumping fuel on the #1 cylinder. Here is what I have done to try and isolate the problem:
verified plug gas soaked
replaced coil
replaced coil wire
replaced plug
swapped injectors
Closed off the nitrious fuel solenoid... In case of fuel leaking through
tested injector plug with a light. Here's where things started looking fishy to me. I noticed the light shining twice as bright on #1 than the rest. So I tested the plug with a volt meter.
#1 read around 11.6
3&5 readaround 6 volts with the car running. (some advice here on default data would be appreciated)

When I first crank the car up my wide band reads fine. After a good warm up and maybe a short drive it pegs my gauge ( blinking 7.5). If I unplug the injector, afr lines back out.This problem just popped up.
I'm running car in open loop attempting to tune the VE.

if anyone has had a similar problem with a solution or someone has some trouble shooting ideas, please pass them along. I'm really thinking this is not tune related but correct me please if I'm missing something. I comfortably know my way around hp tuners, but still have lots to learn. If a scan and tune is needed, I have them.

Thanks

Last edited by sWcCuZ; Jul 17, 2014 at 04:43 AM.

Jul 15, 2014 | 07:33 PM

joecar

TECH Senior Member

Joined: Apr 2002

Posts: 6,080

Likes: 17

From: So.Cal.

Which end of the injector connector did you see 11.6V...?

One end of the injector connector goes to 12V power via a fuse;
the other end goes to the injector driver/transistor in the PCM.

Sounds like you might have a short in the #1 injector driver circuit...
with key on and engine off, with injector connector on injector, what is voltage on driver circuit (i.e. carefully back probe the injector connector)...? You should see 12V (or close to battery voltage).

Do you have a circuit diagram...?

Jul 15, 2014 | 08:48 PM

sWcCuZ

Thread Starter

Teching In

Joined: Feb 2014

Posts: 24

Likes: 0

From: Southeast Texas

Thanks for the reply.
The first time I checked the voltages was with the engine running.

I did the voltage check like you stated and all the injectors tested as you stated they should. battery voltage on one side, ground on the other.

The car can sit at idle in drive way fine.... soon as I start a test drive it bombs again. then once it goes down it stays that way until the key is recycled . double checked plug and same .. gas soaked

Jul 16, 2014 | 07:18 AM

sWcCuZ

Thread Starter

Teching In

Joined: Feb 2014

Posts: 24

Likes: 0

From: Southeast Texas

So what else could possibly cause a super rich condition in just a single cylinder?

Intake runner gasket leak?
Push rod?
If one of the injector wires was grounded out, wouldn't the injector be held either open or closed?

I'm getting a dtc for coil b, and injector malfunction, and cam position sensor

Remeber this condition does not immediately start when engine is cranked. Engine seems to have to be at operating temp to present itself.
Any info at all is appreciated.. Thanks

Cuz

Jul 16, 2014 | 02:30 PM

joecar

TECH Senior Member

Joined: Apr 2002

Posts: 6,080

Likes: 17

From: So.Cal.

Quote:

Originally Posted by sWcCuZ

Thanks for the reply.
...

I did the voltage check like you stated and all the injectors tested as you stated they should. battery voltage on one side, ground on the other.

...

The PCM closes the ground when it wants to fire an injector... so the ground side should be open... when you measure the voltage on the ground side it should float up to battery voltage (because the injector resistance is pulling it up)... it should not be grounded.

Jul 16, 2014 | 02:35 PM

joecar

TECH Senior Member

Joined: Apr 2002

Posts: 6,080

Likes: 17

From: So.Cal.

Quote:

Originally Posted by sWcCuZ

So what else could possibly cause a super rich condition in just a single cylinder?

1. Intake runner gasket leak?
2. Push rod?
3. If one of the injector wires was grounded out, wouldn't the injector be held either open or closed?

1 and 2: no.

3: yes, if the injector's ground wire is shorted to ground then that injector will be held open.

Quote:

I'm getting a dtc for coil b, and injector malfunction, and cam position sensor

There is a clue here... what are the exact DTC codes...?

Also check that all engine grounds are present and have no voltage drop.

Quote:

Remeber this condition does not immediately start when engine is cranked. Engine seems to have to be at operating temp to present itself.

Injector could be sticking open intermittently (or with temperature).

Jul 16, 2014 | 10:07 PM

sWcCuZ

Thread Starter

Teching In

Joined: Feb 2014

Posts: 24

Likes: 0

From: Southeast Texas

joecar, thanks for great advice. it was just enough to push me on track.

when you stated the pcm grounds the injector and thus sends voltage TO the injector opening it, I decided on another test... I waited till the car warmed up again and the car bombed rich, shut the car off with ign key on and immediately tested the injector. it did not swing back up to battery voltage but just stayed at 7volts. I checked 4 of the others and they all read battery voltage, both sides of the wire.

I pulled the pcm blue plug and double checked with my meter I had the #1injector wire, spliced a temporary wire to the black injector plug to pcm.

I let the car sit and idle for 15 min then went for a long drive. pleasantly watching my wideband read in the 14's the entire time. hopefuly this is victory.

thanks again for sharing your time and I hope this thread can help someone else with a similar prob.

thanks