Asking for a little help
I'm frustrated with tuning issues.

I have read through the boards and really don't know where to look. ANY thoughts would be appreciated

I have replaced MAT TPS IAC had everthing tuned by a mechanic.
Replaced fuel pump fuel filter fuel pressure regulator.
replaced all vacuum lines
replaced fan.

tried a different ECM and MEMCAL chip. (all that did was nuthin would only crank and not start.)

and the damn thing STILL wants to intermittently stall unless I feather the throttle

other times she runs like a dream.
I am looking everywhere for a short but have no idea where to start.
Funny I can Fab most anything but I don't know diddly about circuits.

 

what year/engine?

 

how about the timing, are you off by 180? Did you do any work to the car before this happened?

 

Ohhh duuhhh 92 3.1 V6

timing is set at factory 10*
New distributor cap and rotor
plugs and wires
What the heck is left??

 

got the car years ago it drove great for 4 or 5 years let my son drive it for a year and I'm scratching my head wondering what the heck happened? It always drove great. I just made a 1200 mile round trip in it. She drove great aside from a couple of episodes of loosing power at the throttle like it was running out of gas. I would feather the throttle for a bit until it passed. I thought it was bad gas or fuel pump going bad so I flushed the tank and replaced the pump. Had all the other stuff done by a pro with the proper diagnostic equipment. He said the tps was fluctuating and the ECM was bad. So I got one from a running parts car. It wouldnt even start my car. Even after I put my old Memcal in the new ECM

 

If the OEM injectors are still in the engine replace them. Can get a set of Bosch injectors from a sponsor such as South Bay.

The coils of the stock OEM Multec injectors short out. Which cause the exact issues that you describe.

RBob.

 

Thanks I will try that right away.

 

Ya Know I was looking at that link dynamicEFI.com

I was thinking about mounting a net book to the external input port on the new Pioneer touch screen multimedia head for constant heads up display. ERRR?? and cool factor
The price is defiantly in the right range for everyday shade tree guys like me.

 

The EBL P4 that is being released (very soon) will work in your cars ECM. Actually have it running in a 3.1l Camaro at the moment. It is similar to the current EBL Flash system, but with more functionality. And the WUD, although similar, is better looking.

RBob.

 

OK completely lost now.
I just replaced the fuel injectors with the ford 19# yellow tops
Got out on the road and I really noticed the improvement. Until my mystery stutter stalling issue.
So now I have a new fuel system. AND my problem still lingers.
So where do I go from here?
If It is an ECM issue is there a certain installation sequence? or start up procedure because the unit I purchased wont even start my car. I was used but guaranteed to work.

As I drive the car and the stuttering starts some times I can find the sweet spot when I feather the throttle and it clears up. But only sometimes
Would that be in the ECM or TPS? The TPS is new.
Or would it be in the throttle body ??

 

Also the ECM is not throwing any codes. So ???? any Thoughts Gents

 

You realize that 19#/hr injectors are way larger then stock. That alone can cause the plugs to foul, which causes other issues.

For the stuttering/stalling, is this while moving?

If it is at idle you need to do a idle learn procedure. This is for the '90 - '92 3.1l engines. The idle learn needs to be done whenever the ECM losses power (such as being unplugged or the battery disconnected).

Check the wires that run between the ignition coil and the distributor.

RBob.

 

New ignition coil and wires.
The problem only pops up while under load and it stalls,When it happens I drop it into neutral pull over restart while coasting. It runs smooth at idle but as soon as I hit the throttle it dies Immediately. Unless I feather the throttle.(pump it vigorously but lightly)

I went through relearn procedure. No problems
The 19# injectors are working better than I had expected. while on the test run had excellent throttle response and acceleration smooth idle.
Obviously my problem is not in the fuel delivery system.
So Back to square one.

ECM?? the car at one point did have moisture issues.

Distributor ??? It does have 130k on it.

Ground Short??

Where do I go from here??

I was thinking new ECM.

 

I would suggest before you spend any more money, you make a real effort to pinpoint the cause of your trouble. A fuel pressure gauge, spark tester and scan tool can be connected to the car and the car driven to recreate the trouble and watch for changes in fuel pressure, spark drop out, shifts in ECM data. There are many things that could be causing your trouble. From a bad ECM to a simple wiring issue. All the new parts in the world wont help if you have wiring trouble.

Your mechanic mentioned TPS fluctuations. The 3.1 had a problem with worn throttle bushings that would cause irregular TPS readings and a resulting innability of the ECM to establish adaptation of idle and fuel maps. In other words, the engine would act up for no apparent reason and stall or lose power. Your description seems close to what I've experienced with this before. You may want to take a close look at your throttle shaft bushings.

BTW, as a drivability student in GM tech school, I was taught that if you think it's got to be the ECM, look again. ECMs rarely fail. Its much more often a misdiagnosed electrical or mechanical issue that is blamed on the ECM because the mechanic gets lost. For what it's worth.

Oh, and your new ECM not working could be a mismatch in the VATS program. There were two different signals used for fuel enable which changed about 91-92. You may have gotten an ECM with the wrong program that doesn't recognize your car's VATS module. Just a thought.

 

it sounds like one of your vital sensors may be down

 

The coil to distributor wires, this is the two wire power/grounds between them. There is a pink and a white wire usually in a convoluted sleeve. Sometimes they rub through on a bracket. Sometimes they break internally where they enter the connector body (mostly at the coil end).

By your description it sounds like either the spark is dropping out or the fuel pressure is dropping off. Fuel pressure is easy to check. The test point is between the distributor and rear of the plenum. Hook a gauge to it, start the car and whack the throttle.

Spark: pick up coil or ignition module. Other items I've seen with the distributor: loose base plate (cap wobbles around), and the star wheel loose on the shaft. Both are easy to check.

RBob.

 

OK Thanks so much guys I was just so frustrated and didn't know where to even start. Thank you so much
Looks like I have my work cut out for me today.
I will keep you posted.

 

OK here is the update. and what I found. The ECM was not Mounted I pulled the panel and it fell out. The plug in retainers were loose.
I pushed them all in securely and then secured them with duct tape.
Screwed it down tight.
Found a cracked vacuum line the small 3/8 in line that goes to the fuel pressure regulator. Fixed
Still running like crap but a little better.
Then I crawled on top with a flash light and saw that the distributor cap was pinching the green and white pick up wires
from inside unscrewed the cap pushed them back under.
still ran like crap on the way to work.
On the way home from work it ran awesome. Lets hope the problem is fixed. (fingers crossed)
By the way I need to say thank you to all of the folks on this board for all the help.
Since I have joined I have literally saved hundreds if not thousands in parts and shop labor fees.

 

if you talk to your car a lot things magically fix them self sometimes and when you ignore it things break just saying. hope your problem stays fixed

 

Nahh you just turn up the radio

 

try the throttle postion sensor