#5 not firing right

[Lapkritis]

I think you've got it narrowed to the injector or harness connector that attaches to the injector... perhaps the pins are loose or have light corrosion. Electrical contact cleaner in there might not be a bad idea incase it's an oil layer that's holding the show up. Otherwise I would replace the injector. Never hurts to have a spare or two anyway so if you have one spoil during a race you don't lose the whole weekend.

[JJ 911SC]

Originally Posted by Walt Fricke

I'll see if I can do that. The software has startup enrichments, which are for set durations.

Walt,

Last weekend I had everything adjusted right through the VE table. At the time the engine was close to normal operating temperature. Last night it would almost would not start with a cold engine, after a while it stay running long enough so I could make it to the throttles and open it to raise the RPM 500 to 1000 RPM, so I'm also need to do some startup enrichment as well so but have not figure out which part of the software and how.

If # 5 injector is the main suspect, you could switch it with # 2 (you may have already done that)

[Walt Fricke]

Bob - #5 has vacuum (air flow, anyway) at idle. Just a bit lower than others, and unresponsive to idle air screw adjustment. When I had the ITBs off the manifold I squirted carb cleaner through the passageways for that. Made no difference. It gets enough air (and spraying starter fluid makes it run, so that shows air also).

If the butterflies were culprits for air leak, I'd think that would go away at 2,000 rpm or above. Doesn't.

I'm about to send the ECU off. The only connection not checked is the male on the ECU itself which holds the female on the big plug from which the common 2/5 injector ground comes. Those connectors all look to be the same, fine, etc. And good enough to fire 2. They are basically sealed, and have no oil/grease on them.

I do have contact cleaner, and I guess I could spray that on that part of the big plug. I've already done that on the injector connectors.

And since this is the 3d injector not to work in #5, I'm not suspecting injectors as such. Something is wrong with the ground, and that only happened inside the ECU.

Off to DE the SC and forget this problem for a weekend if I can.

Thanks all

[HawgRyder]

Walt...depending on the circuitry inside the ECU...you could have a heat induced problem.
If a semi conductor is not properly heat-synced...it can run into overload or runaway very quickly.
When it cools down it sort of "heals" itself again.
I don't know the inside of the unit..so this is a general possibility.
I understand that all the injector fire at the same time...but you have stated that it is possible to use this same box as a sequencial injector firing device...which would suggest that each injector is attached to its own trigger inside the box.
So...if the firing device (transistor/SCR/Triac/ or whatever) is faulty on #5 only...no matter what you do outside the box will not fix it....connectors/wiring/etc.
I think we have narrowed it down to the ECU...now just a matter of having a competant tech open it up and give you the answer.
Hopefully, they fix yours...and tell you what they found...rather than just exchanging the box and you never know what the problem was.
Bob

[fred cook]

Walt,

Have you or can you check the fuel pressure at the #5 injector? All of this sounds to me that the cylinder simply is not getting fuel. You have eliminated problems with compression, leak down and spark to all that is left if fuel. Could something be blocking or partially blocking the fuel flow to the #5 injector? Also, have you checked the electrical signal going to #5 injector? I know that you said #2 and #5 were fed from a common source, but you could have a break or partial break or high resistance in the wire to #5 beyond or at the wiring split. Maybe you could put a test light on the #5 wiring harness plug and let the engine run to see if that lead is firing consistently?

[thumbdoctor]

Another idea (thinking out of the box again). Is it possible the cam lobes for #5 are worn through the case hardening and the valve lift has been compromised. Seems to me you have exercised most other symptoms. Could explain the compression anomalies and the reversion cause by an incomplete combustion cycle will affect manifold vacuum. A vacuum gauge connected will have a unstable reading if valve seating or lift is compromised while engine is running.

[JJ 911SC]

Well I got the same problem; The engine was not running smooth so I unplug the injectors plug one by one and when I got # 5 no sound or idling change...

Now I got to read this thread again and go through the faultfinding did. As 2 & 5 are fired from the same DFU coil, I'll switch them around.

[JJ 911SC]

Originally Posted by Walt Fricke

... Something is wrong with the ground, and that only happened inside the ECU...

Well, I think that is where I'm at. Not to hijack the thread but to add on.

Last week I took the first "3 minutes" ride (first one since December 12) to do data logging after finishing installing the TEC/GT with PMO EFI on my 3.2.

It did not sound right and mention to some of my Porsche buddies that if feel like I was running on 5 cylinders but brush it off as it needs tuning. Got back to it this weekend.

So this morning when it was running at a quasi steady idle, I unplug the injector connectors one by one starting with #1 and on, every time the idling would go down but when I got to #5 there was no change when unplug and plugged back. #6 was as the other working 4 cylinders. I also confirm with a mechanical stethoscope that #5 was not "clicking" while the other 5 were.

Next, I took a temperature reading at the headers of each cylinder and # 5 was half the temperature of the others.

Borrowing on Walt faultfinding, I switch the spark plug wire #2 and #5 on the DFU coil C. The problem remain with #5.

After putting them back to their original position, I replace #5 spark plug wire with the CE one that I was using before. No change # 5 is not firing.

Checked and confirmed that the 12 Volts is present at the injector connector (as mentioned in previous post, the ground to energized the injector, is supplied by the ECU).

So to eliminate the injector itself, I removed the spark plug wire on #5 (to avoid ignition) and put #4 injector connector on #5 injector. Listen to it with the stethoscope and it was clicking like there was no tomorrow so the injector is good.

Next, I ohm out the "ground wire for the #5 injector", pin 4 from the 35 pins GRAY Connector to the injector connector and it showed perfect continuity.

As per Richard suggestion at post #47, I checked the tightness of the connector. Pin 4 female receiver is as thigh as the others one. The pin itself on the ECU is OK and lined up with the others in both plane.

So I'm not getting the ground pulse from the ECU for cylinder #5.

Not being sure if a software glitch could do that but I did a new program, loaded it but #5 injectors still not getting the ground pulse.

I’ll contact Richard tomorrow to see if there is anything else I should do.

[Walt Fricke]

JJ - misery loves company! Hijack away.
I hadn't thought of attaching the 4 or 6 connector to 5, but I'll try that. However, in my case the #5 injector clicks away when connected to the #5 connector, which increases the bafflement. It seems to click but not squirt. Not the injector itself, as shown by switching injectors around and other tests. Likely not the wiring, as shown by swapping sides with the wiring, and various other tests. Starting to point more strongly to the ECU, despite improbability there.

Thumbdoctor - visual inspection of cam lobes (in situ, but you can still see much of the lobe and watch the rockers rock) shows #5s seem like all the others. I believe that a combination of no oil squirted on a lobe, plus wearing through hardening, leads to very rapid wear. Which makes the oil look gray. My oil looks like fresh oil should look. Plus artificially adding fuel (starter fluid) or "manually" causing the injector to squirt (9V battery and tapping lead to battery) would seem to rule out mechanical issues.

Fred - no convenient way of checking fuel pressure only at the #5 port on the fuel rail. A guy would have to machine a sort of injector like fitting with a pressure fitting to do that. But physically there seems simply no way for pressure to be different there - the fuel system is looped, so both rails on both sides are fed directly from a T fitting, and both come together separately at the regulator. I've physically inspected the fuel rail.

I've also checked the electrical signal using an LED (with a resistor) as a low buck NOID (don't know where that name came from). It flashes like it should. And also by measuring resistances in the wiring, plus swapping sides with all the injector wiring. And, as mentioned, the #5 injector clicks just like the others do.

But still fuel isn't being squirted out of that injector.

Bob - the TEC3r has extra outputs which I don't use. At least one of them is so it works on 8 cylinder automobiles. The others are for use with full sequential. I've toyed with the idea of maybe using one of those to make the #5 fire, but haven't memorized/internalized the manual on all that enough to figure out if that could be done.

This doesn't seem heat related, as the lack of fire is the same with the engine dead cold and just started up as it is with it at least warm from running at idle speed for quite a while as I futz around with this or that scratching my head.

But the box most likely is soon to be sent back to Electromotive for them to check out.

Brandon told me of a similar issue with a carbureted engine, although his problem had been only at idle. One of the butterflies got out of adjustment, so it was not cracked a little when the shaft was on the adjustable stop, but the others were. Thinking what effect having a motor blow up with these ITBs attached might have on the problem, this at least got me thinking, as debris from the exploded #6 was blown up into the air filter, and at least some of it and some of the oil was sucked down the #5 on that engine. It had to pass through the #5 ITB to do so. But a) the #6, which had the most debris flow, seems to work fine, and b) this problem does not seem to go away above idle, and c) unlike the Webers, this model of TWM has a single solid rod shaft holding all three butterflies. Also, the air bleed is supposed to let the motor idle with a fully closed butterfly, I believe.

But I'm going to check butterfly closures. He told me how: crank the idle stop up so that a small drill bit will just pass, say, the #4 butterfly. Then see if it will just pass the other two. As long as you get it at the 90 degree point away from the shaft, it avoids worrying about the fact that feeler gauges are kind of wide.

Walt

[JJ 911SC]

Originally Posted by Walt Fricke

JJ - misery loves company! Hijack away.
I hadn't thought of attaching the 4 or 6 connector to 5, but I'll try that. However, in my case the #5 injector clicks away when connected to the #5 connector, which increases the bafflement. It seems to click but not squirt. Not the injector itself, as shown by switching injectors around and other tests. Likely not the wiring, as shown by swapping sides with the wiring, and various other tests. Starting to point more strongly to the ECU, despite improbability there...

And it sure point it that way in my case. Success at last but it does not feel good...

We were able to make contact with the ECU pin while the connector was on and hook it up to a LED light which light up signalling that the ECU was putting out the ground pulse that did not reach the injector. Even though the "grabbing fit" of pin 4 was as good as the other, it was loose enough not to make contact with the ECU pin.

While the Tech Tip does mention that a loose female pin receiver may generate some bad sensor reading, this is a brand new kit so I'm baffle to why that would happened.

Once pin 4 was tightened up, #5 injector start clicking and the idling smooth out. As the plugged connector was move around the engine start loosing rev but the LED on #5 was flashing steadily!!! It only meant that another connection was loose.

So we move the LED light around all injectors and pull the ECU connector in all directions (left, right, up and down) and shake it all around. When we got to inject #3 the LED would stop flashing as the ECU connectors was move around. So pin 3 had also some loose in it. Pin 3 was also tighten up and every injector was running OK while the ECU connector was pull in all direction. It might be coincidental but the two loose pin connection happened to be side by side.

Having work with MIL spec connectors all my life, its the last thing I would expect from a new connector use in a sport car.

Walt,

While your #5 injector is clicking, you might want to scope the pulse and compare it to one that is working.

Hang in there, it will get solve. In the meanwhile enjoy a cold one;

[Lapkritis]

Ecu sent in yet?

[thumbdoctor]

With the engine running and 12 volts applied to one side of the injector, ground the other side and see if it floods. WOT usually grounds the injectors momentarily. This may support the bad ECU theory.

[Lapkritis]

Walt, Did you ever figure this one out? If so, what was the cause?

[JJ 911SC]

Originally Posted by Lapkritis

Walt, Did you ever figure this one out? If so, what was the cause?

Kind of funny I was thinking the same on Sunday!!!

Mine turn out to be a connector problem at the ECU plug (brand new).

After the not so good experience, I decided that I wanted to be able to monitored every signal anytime anywhere, so I did a "giant" breakout box.

Me and a buddy re-did the whole plug from new parts. Kind of time consuming but the Winter hang around for 4 months here so I got to finish it just in time as the snow disappear


Before

[/QUOTE]

Borrowing the idea, of being able to "monitor any signal" from Trog, here is the result of my procrastinating almost finished winter project...

Started on the second try, after plugging the 12 volts to the DFUs

[Walt Fricke]

Picture 2 is quite an improvement over picture 1!

I've done something sort of similar going crazy with fuses and screw clamp wire connector blocks, although mine are mostly up front. I had to make up a wiring diagram, as I've forgotten what is what.

My puzzling motor sits in the garage. Maybe it will heal itself?

My latest brainstorm is to put a vacuum gauge on the hole and see if it holds vacuum with the valves shut. I could try that first at the throttle trumpets, I suppose, being careful to find and block normal vacuum lines. Then with the TBs removed. Then with manifolds removed. It was suggested that I try to swap sides with the TBs, as another way of chasing a leak. But that would call for some jiggering, though the idle stops should substitute for any throttle linkage.

I've been busy chasing issues with my SC backup race car. Doing my PCA race officiating thing. Got a leak in the roof to find and fix.

If I find a cure (or at least a cause), it will promptly appear on these pages.