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Fuel Injection Problem Driving Me Nuts! FI Pro's Please Help, Stock 87 GT 5sp by Ponnari
Started on: 11-07-2014 05:57 PM
Replies: 21 (436 views)
Last post by: Hudini on 11-16-2014 10:21 PM
Ponnari
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Report this Post11-07-2014 05:57 PM Click Here to See the Profile for PonnariSend a Private Message to PonnariEdit/Delete MessageReply w/QuoteDirect Link to This Post
Stock 87 GT 5sp, 110k miles, original injectors.

Hello everyone,

Need some help from the fuel injection pro's out there, please. I am working on a stock 87 GT with recent tune with all GM parts. The car ran great for about a thousand miles. Then, one day went to start it and it ran very badly, like it was only running on some of the cylinders.

Found the problem (kind of) which was a blown fuse for the front bank of injectors (2,4,6). Replaced the fuse, car started and runs much better but still not like it used to.
It has a rough idle, but runs closer to normal as RPM's increase.

After checking a lot of things here's what I found...... on the rear bank of injectors (1,3,5) when I pull of a spark plug wire one at a time (while running) the engine stumbles and shakes until the plug wire is plugged back on (just like it should). It is all the same for each (1,3,5) cylinders.

Now, when I do the same procedure of the front bank (2,4,6) it only makes a slight difference on how the motor runs when I unplug each spark plug one at a time. All three cylinders act the same when unplugged.

I've tried everything I can think of including searching PFF's for solutions with no luck

Question is, I am planning on swapping the ground signal wires from the ECM (Lt Blue & Lt Green on the plug) to the opposite banks to see if the problem switches banks also. That way I can determine if I have a wiring or ECM driver issue. (Wiring color chart below).

I'd like input from the pro's on this, and any other suggestions that might help. Thanks in advance for your help & suggestions!

A - Pink/White - Switched power - runs to the injectors with the Lt. Green wires
B - Lt. Green - Injectors to ECM
C - Lt. Blue - Injectors to ECM
D - Pink - Switched Power to the injectors with the Lt. Blue wires
E - Purple/White - Cold Start Injector
F - Tan - Cold Start Injector

------------------
"Because in a split second, It's gone"

Ayrton Senna

[This message has been edited by Ponnari (edited 11-07-2014).]

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Gall757
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Report this Post11-07-2014 06:40 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
Do not pull spark plug wires on a Fiero when the engine is running. You will eventually damage the ICM and possibly the ignition coil. a 60 degree V6 should run smoothly on 3 cylinders. If it does not, something is wrong with the 3 cylinders that are firing. I suspect junk in the injector...have you had them cleaned?
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Ponnari
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Report this Post11-07-2014 06:44 PM Click Here to See the Profile for PonnariSend a Private Message to PonnariEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks,

Injectors have not been cleaned other than running 1/2 bottle of Seafoam added to the gas (5gals) after the problem started.

I was hoping not to have to tear it apart
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Gall757
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Report this Post11-07-2014 07:58 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
I had to run about 4 doses of injector cleaner through mine before it got better. You may be able to keep at it and avoid taking them out.
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phonedawgz
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Report this Post11-07-2014 11:25 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
The real problem is the rough idle right?

A non fully closing EGR valve is a common cause for a rough idle. Remove the valve, clean out the carbon deposits from the seat and pintle. Make sure the pintle is extending enough to fully close the EGR passage.

---------

Yes you can swap the injector wires and see if your 'trouble' follows.

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+1 on never pulling plug wires on a running engine with electronic ignition.

[This message has been edited by phonedawgz (edited 11-08-2014).]

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Ponnari
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Report this Post11-08-2014 01:13 AM Click Here to See the Profile for PonnariSend a Private Message to PonnariEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks phonedawgz, yes rough idle is the biggest problem, and motor not running as crisp as it did.
I will try both and update.

[This message has been edited by Ponnari (edited 11-08-2014).]

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phonedawgz
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Report this Post11-08-2014 11:34 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Leaking EGR (not EGR tube) problems show up most at idle and low air flow conditions. If you have this problem at WOT or near WOT, then look elsewhere.
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85 SE VIN 9
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Report this Post11-08-2014 04:50 PM Click Here to See the Profile for 85 SE VIN 9Click Here to Email 85 SE VIN 9Send a Private Message to 85 SE VIN 9Edit/Delete MessageReply w/QuoteDirect Link to This Post
Wasn't there someone with almost the same problem a few months ago? It turned out to be an iffy wire to that bank of injectors.
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Ponnari
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Report this Post11-10-2014 03:45 PM Click Here to See the Profile for PonnariSend a Private Message to PonnariEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks everyone!

I will be trying all of the above suggestions and post the results.

Any others want to chime in with ideas?

------------------
"Because in a split second, It's gone"

Ayrton Senna

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Dennis LaGrua
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Report this Post11-10-2014 06:30 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Your injectors are 27 years old and so is your fuel pump. Check fuel pressure at the rail and with a test light verify that all injectors are being energized. If that checks out it may be time to get the injectors cleaned and flow tested.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

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Ponnari
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Report this Post11-11-2014 07:34 PM Click Here to See the Profile for PonnariSend a Private Message to PonnariEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks "Dennis LaGrua" that is good advice if I were having issues on both banks but that is not the case. Your post doesn't address my question. Plus this happened instantly, not over time (re-read my first post & others that responded).

It is almost impossible for all 3 injectors themselves on one bank to mechanically / electrically fail at the exact same time. It is more likely that it is an ECM driver, or some other type of an electrical issue.

There has been mention here on the form of the exact same problem, unfortunately after searching I could not find were anyone solved their problem on other posts. Therefore I am still troubleshooting, and hoping someone else has had this issue and found the problem.
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Report this Post11-11-2014 08:55 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
Injectors do not fail evenly. If there is a bad connection or blockage in one of them, the symptoms will be as you have described. It would make no sense to clean and flow-test just one injector, however, so they are always done as a group, as Dennis has suggested.
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Ponnari
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Report this Post11-11-2014 09:06 PM Click Here to See the Profile for PonnariSend a Private Message to PonnariEdit/Delete MessageReply w/QuoteDirect Link to This Post
I do have brand new sealed OEM injectors & presure regulator, ready to install if I have to go that route. Only place I have to work on the car is outside and it usually rains here when I get a day off
so replacing injectors will probably have to wait for spring unless I can fabricate some type of tent over the back of the car to keep things dry.

[This message has been edited by Ponnari (edited 11-11-2014).]

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85 SE VIN 9
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Report this Post11-11-2014 10:45 PM Click Here to See the Profile for 85 SE VIN 9Click Here to Email 85 SE VIN 9Send a Private Message to 85 SE VIN 9Edit/Delete MessageReply w/QuoteDirect Link to This Post
Rent a storage unit?
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Dennis LaGrua
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Report this Post11-12-2014 04:56 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Ponnari:

It is almost impossible for all 3 injectors themselves on one bank to mechanically / electrically fail at the exact same time. It is more likely that it is an ECM driver, or some other type of an electrical issue.
.


Then check the injector harness for that bank. I thought that my advise to test for a signal at each injector was worthwhile but I guess not!

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

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Ponnari
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Report this Post11-12-2014 05:26 PM Click Here to See the Profile for PonnariSend a Private Message to PonnariEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi 85 SE VIN 9, good idea. I looked around locally within a few miles but the problem is I am close to the city and they are so regulated (no working on cars, boats, etc. it's in the contract ) and they all have video surveillance, which sucks! lol
Thought about trying it anyway......

[This message has been edited by Ponnari (edited 11-12-2014).]

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85 SE VIN 9
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Report this Post11-12-2014 10:32 PM Click Here to See the Profile for 85 SE VIN 9Click Here to Email 85 SE VIN 9Send a Private Message to 85 SE VIN 9Edit/Delete MessageReply w/QuoteDirect Link to This Post
Yeah, it also depends on the market. There are many more around here so the rates are lower. It's might be in the contract here too, but they even told me I could use the power from the light. It's working out very well. It's cold now, but the heat of the engine is enough to work a couple hours in comfort. You can get those tent things, but that might be more trouble legally than working in a unit. I really suspect it's just one wire you need that you could do in between the raindrops. Look under lack of power or no power mid range, or something like that. It was not that long ago. Check the wiring diagrams, then check the wires from the injector fuse and the ground. If it's like the other guy there will be one of those that has extra resistance or no continuity, is loose, or intermittent.

[This message has been edited by 85 SE VIN 9 (edited 11-12-2014).]

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Ponnari
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Report this Post11-13-2014 03:16 AM Click Here to See the Profile for PonnariSend a Private Message to PonnariEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks "85 SE VIN 9" , I agree about the wiring. If it will stay dry I'm going to try and brave the cold and do more testing.
also, I'm going check more storage places and ask them off the record about working on cars

------------------
"Because in a split second, It's gone" Ayrton Senna

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sardonyx247
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Report this Post11-14-2014 05:26 AM Click Here to See the Profile for sardonyx247Click Here to visit sardonyx247's HomePageClick Here to Email sardonyx247Send a Private Message to sardonyx247Edit/Delete MessageReply w/QuoteDirect Link to This Post
Did you ever reset the ECM after replacing the fuse?
And after the reset, drive the car over 25mph for a little bit, then turn off the car and start it again. This resets the idle.
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Ponnari
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Report this Post11-14-2014 11:39 PM Click Here to See the Profile for PonnariSend a Private Message to PonnariEdit/Delete MessageReply w/QuoteDirect Link to This Post
I did reset the ECM, but ya know it might be worth doing again.

------------------
"Because in a split second, It's gone"
Ayrton Senna

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Report this Post11-15-2014 09:19 AM Click Here to See the Profile for tesmith66Send a Private Message to tesmith66Edit/Delete MessageReply w/QuoteDirect Link to This Post
Sounds like you have a bad injector (electrically) on the 246 side. They are wired in series (per side), so if one goes, they all behave in the same manner.

------------------
1986 SE Aero coupe.

3.4 DOHC swap is complete and running, now just have to finish the rest of the car...

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Report this Post11-16-2014 10:21 PM Click Here to See the Profile for HudiniClick Here to Email HudiniSend a Private Message to HudiniEdit/Delete MessageReply w/QuoteDirect Link to This Post
IIRC (and I do not have my wiring diagrams with me) all 6 injectors fire at the same time. Each bank has it's own power through 2 fuses, but the grounds to the ECM drivers are wired to fire all 6 twice, not 3 and 3. You could still have an issue between the harness connector and the point where the grounds are spliced together.

The single blown fuse suggests a short between the fuse panel and the affected injector bank.
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