Dear Ferraristi,

Just made it home !

I have a problem with the engine shutting off on my 91 Testarossa ( US Version )...just like that.

I was driving this morning and while in an area with speed bumps, the engine stalled. I thought at first, I didn't let the clutch out right and started it up right away and was off. I didn't think anything of it.

Coming to my home for lunch, the problem happened again...just two blocks from the house. I was driving and with no warning, the car stalled. All the gauge needles dropped with the red oil light coming on. ( just like if you had the ignition in pos II before you start the car. )

I put the clutch in and twisted the key. It fired up and then stalled again. I tried again and it sort of came to life. I put my foot in it and revved it up and got me going to my driveway. I pulled in the driveway and the engine was slightly rough. While I waited for the garage door to open, the car didn't stall but was still rough. While in the garage with the engine still running rough ( not big-time ) I jiggled all the connectors I could find...no avail.

I went to the fuse box and jiggled the relays...no avail. While it was still rough, I pulled the the fuel pump relays one by one and could hear the engine go down on each bank. I would put the relay back and it would come back....but still slightly rough.

Then without doing anything, it started running smoothly again.

- I don't think it was the fuel pumps or relays as the car would fire right back up without hesitation but would promptly stall again.

- I don't think it was a loss of electrical power as the car still had power to start up a few times in a row.

- When in the garage at idle, car was running, fans on (normal high speed...not diminished ) but engine slightly rough.

What would cause the car to stall out without warning? Again, I would start it and I would get a couple of seconds of running then stall out.

I've never had a stall while running problem before. I don't even know where to start. All connectors are tight clean and corrosion free.

Please advise !


Shamile

Freeze...Miami Vice !

i'm sorry i can't help you with a fix, but i can tell you what i had my 91 tr engine die and start and die and idle poorly and it turned out to be bad fuel.... we checked everythig out and it was the fuel...they had to drain out the old fuel and put new in and it ran great after that.....i had bought fuel at a low end station and it was no good...(i don't buy fuel there anymore),it may not be your problem but it is something to check out in this day and age......

Dear Ferraristi,

Thanks Fred but I've had the same tank of fuel for the last four days. Since my car is a daily driver, it has been driven everyday since.

Took the afternoon off from work to post some measurements...

Started car....yeah sure, runs fine now.

- With Timing Light...all plugs firing.
- Multimeter...battery at off 12.8V. Idle or high revs, fans on, 14.6V...battery OK, Alt OK,

I remember that if the tacometeric sensor or TDC sensor is off, car will stall out. I pulled both sensors and both were covered in grime. I do have a very very small crank seal leak and the sensors were covered in black residue...very grimey but not wet. I cleaned them both to death and put back.

Ran the car in the garage for 1/2 hour at multiple rpm speeds....no issues, no roughness.

Could the sensors just covered in grime not pick up the signal and stall the car out?

When cleaned, I ran the car and slowly pulled each sensor out (one at a time ) till the car stalled. It took very little distance before the signal was lost and the car stalled. I tried where I pulled each sensor ( one at a time ) and while the car was dying, put the sensor back....the car picked up and ran like normal.

When the car did stall by the sensor removal, the dash gauges were just like when it stalled on me. All needles down ( except coolant/ oil temps and fuel) Oil pressure showed red light.

I'm not saying I solved anything....just going down the potentials list.

BTW, wouldn't a problem with the tachometric relay stall the car out? ....how do I confirm / deny...Oh Steve Magnisun...hello?


Shamile

Freeze...Miami Vice !

Shamile -- Got your PM, but it's better to discuss here so I can post pics, if necessary. Your symptom (sometimes crappy running needing throttle to stay running) is probably more +12V power/protection relay related rather than tachometric relay related -- IF it is an injection system electrical problem (and assuming that you have a US version F113A040 TR engine). The tachometric relay does run the fuel pump relays, which run the fuel pumps, so that's sort of works, or doesn't work, situation, rather than some sort of intermediate crappy running mode. Same thing for the flywheel sensors -- usually either works or doesn't -- very rare to get some condition that runs poorly. However, losing the +12V power to run the KE injection system does give a crappy lean runnning condition that needs throttle to stay running. See this thread post #8:

http://ferrarichat.com/forum/showthread.php?t=202424

for the first couple electrical tests that you can try (if you can get the problem to reappear consistently -- if it ain't broke, you can't fix it ).

Dear Ferraristi,

I dug though the archives and schooled myself in the wisdom and achient teachings of Jedi Master Steve Magnusson. Yes his voice traveles though the ages in webpage after webpage of Bosch KE jetronic teachings.....


OK,

Before I got todays post, I went through your previously posted threads.

My problem....the car is still running fine.

- measured 12V on cranking & running on violet lead on connection X in fuse box ( tachometric signal ) OK

- measured 12V on red lead on thermoswitch on running. OK

Since I can't duplicate the stall out / rough running, I changed the tachometric relay anyways....had a brand new spare

Since the car runs just fine, all tests on the protection C relay confirm.....I ordered a new protection C relay anyways. ( from your old post $85 to $110 now ) The original one has 1991 stamped on it.....umm days of a 486 computer + 48000K miles later.

I did notice that when I changed the tachometric relay, one of the female spades in the white connector was pushed out of the holder with the retaining pin bent back...meaning that the spade was just sitting in the plug....not fastened in to receive the male spade of the relay. I bet the male spade was just pushed up against the female spade but not connected in the plug.

Have now got the protection relay box appart for terminal cleaning.


Shamile

Freeze...Miami Vice !

Steve,

Yes my 91 Testarossa is a US version F113A040 TR engine ( checked it just now )

When you say " losing the +12V to the KE injection...." do you mean at the C protection relay....meaning because the relay is crapping-out, this is now happening?

Or, do you mean losing the +12V to run the KE....is from somewhere else?

I did the first test...OK

Can you please explain the second test. If I connect the leads to the injection ECU and follow the chart resistance/ temp....what am I looking for? What is considered "bad". Also, what sensor is this test for. I understand it to be the black molded plug ( moved on from the thermoswitch)

BTW, in the wire connector on the molded black plug on the water housing, I found a resistor soldered in place. It's been there since I bought the car 7 years ago. don't know why it's there...car runs great....why touch it?


Shamile

Freeze...Miami Vice !

Dear Ferraristi,

I thought I would post Steve's pix from the other thread so we can all see and learn...

This is the test I questioned in my last post.

BTW, since there two injection ECU's...do you test on both or does the signal from sensor just goes to both...meaning, testing one is the same result for the other?


Shamile

Freeze..Miami Vice !

Attached Images

 

No no...my mistake.

The resistor is soldered in the brown molded plug wire not the black one. The black one is unmolested.


Shamile

Freeze...Miami Vice !

Dear Ferraristi,

Found this in one of Steve's posts.....

1. Find the water temp switch pointing out the LH side of the thermostat housing (it is not either of the gizmos on top of the thermostat housing with the molded connectors). It will have 2 separate spade-type connectors -- one red wire and one orange/black wire. The red wire is the main +12V supply from the relay "C" in the black triangular box to run the injection system. This wire should be +12V during starter cranking and during engine running.

OK, +12V FROM the protection relay C to the thermoswitch......yes?


Shamile

Freeze...Miami Vice !

Could be either, and you'd have the same result -- no +12V power to the KE-Jet injection ECUs (for whatever reason) = no current in the EHAs = lean). The food chain is +12V battery terminal -to- +12V battery cable going to the starter solenoid post -to- protection relay -to- injection ECUs -to- water thermoswitch on the side of water housing. IIRC, people have found multiple problems in various places over the years -- bad terminal/wiring on the GR wire going from the starter solenoid post to the protection relay, bad protection relay itself, bad fuse at protection relay, etc.. But you're always going to pass this test if it's running fine now

  Yes, that test is for measuring the resistances of the 2-channel "black" (forwardmost) coolant temperature sensor mounted on top of the water housing. The resistance of each (separate) element (when it's working properly ) decreases with increasing temperature so these are often call "NTC" sensors (for "negative temperature coefficient" sensor meaning the slope of the Ohm vs Temp curve is negative). You make the resistance measurements between the female teminals in the unplugged injection ECU connectors on the wiring harness side (not on the injection ECUs themselves). You don't have to match the chart super-exactly, but if was off more than 15~20% in either direction (at the cold start temp or the warm shut off temp), you could replace it without regret IMO (and, if it isn't off, there's no need, nor benefit, to replace).

Ohhhh boy !

I though I was getting ahead here.

I think I will take the most likely result based on my symptoms.....car stalled, restarted....stalled again, restarted...ran rough...had to run higher revs....still ran rough at idle in the garage...then went smooth. The most likely based on Steve's posts....protection C relay. I'll have to drive it close to home for about a couple of weeks to verify (hope ) I got it.

BTW,

test #2 so far.... stone cold engine...1.425 K ohms on pins 2 & 21 of the injection ECU.


Wondering,

since you mention that you can bypass the protection relay( for testing ) ...terminal 30 & 87...can I run this way...further testing? The 10A fuse is not blown. If I put a 10A fuse in between the jumper...am I ok? ....till the new relay arrives?


Shamile

Freeze...Miami Vice !

Ahh...no !

You cannot run the car this way. While bypassing the relay is ok for testing, it energises some other relays so if you leave the bypass in place, it keeps things energised even with the key off.....doubt that can be good.

I only noticed this as I was testing the grip of the female spade (key off )and while I pulled out the jumper, I could hear what sounded like relays clicking. I put the spade back in and....click again.

Sighhhh....I have to wait for the new relay.


Shamile

Freeze...Miami Vice !

Steve,

Here are some values I measured on the thermomister / ECU plugs

(F) Front ECU plug

(R) Rear ECU plug

Stone Cold

F 1.832 K Ohms
R 1.928 K Ohms

140 F

F .594 K Ohms
R .650 K Ohms

167.50 F

F 9.78 M Ohms
R 9.80 M Ohms

192 F ( Fans turn on )

F 232.1 Ohms
R 256 Ohms

Is this in range? Do you find the values acceptable?


Shamile

Freeze...Miami Vice !

Please give a temperature for "stone cold" (i.e., the ambient temperature before starting).

The 140 def F and 192 deg F resistance numbers look quasi-OKish, but there's definitely something wrong with the 167.5 deg F numbers (most likely something in your technique or the instrument settings) -- no way both would be MegaOhms, and very unlikely both devices would be OK at temps just below and just above the 167.5 value.

Thanks for your response Steve.

The odd temp numbers were based on the notches on the temp gauge.

Stone cold: engine off overnight ( tested at 3 PM ambient air temp 90F )

140F : 140 mark on gauge

167.50: middle notch on gauge between the 140 & 195 marks

192 : Fans come one / needle pointed just below 195

On the measurements: I was using my multimeter set to the Ohms setting. I was only reading off the meter. Since you say something is "off"...I will do it again and repost.


Shamile

Freeze...Miami Vice !

when you take measurements, sometimes it's good to make sure the the wire is properly plugged in the multimeter.


Ambiant air temp 92F

(F) Forward ECU
(R) Rear ECU

Cold ( engine cold overnight)

F 1.67 K Ohms
R 1.77 K Ohms


140F

F .644 K Ohms
R .626 K Ohms

167.5F

F 367.4 Ohms
R 364.2 Ohms

192F (Fans turn on )

F 238 Ohms
R 250 Ohms

Soooo, what does it mean?



Shamile

Freeze...Miami Vice !

Dear Ferraristi,

Well, got the Miami Vice machine running just before Sat. night. I went through all the test procedures Steve recommended.

One of the problems was that the red connector and the spade to the thermoswitch had oxidized. It sits underneath right at the edge of the engine cover in the center of the engine hatch. When it rains, the water rolls off the cover directly on connectors. Even though I had mentioned that I had cleaned all connectors...that was a few years ago. Since my car is an all weather daily driver, the connections were badly discoloured and the female connector had widened out.

I cleaned them to death and the car seemed to run better. Trouble also seemed to lie in the protection relay C. I replaced it with the new one I received Sat. morning. I put it in and everything was running smooth.

As I was putting the wiring back in the box, I noticed the engine trip out again. After 4 straight hours of testing....on a roll here....just couldn't pull myself away.....I found there was a fault in the new relay.....the ground pin! I just couldn't believe it. It had got to the point that I pulled all the connectors out of the moulded plug and ran them directly to the relay. By moving the wires, I could get it to trip out. By working backwards and doing connectivity checks with my multimeter...I found if the ground spade on the relay was moved slightly....the connection would break. Put the old relay back!!

Ok, go for a test drive...all OK !

....or so I thought !


Shamile

Freeze...Miami Vice !

Dear Ferraristi,

I thought everything was OK, so I drove the car to work today. Well, at least I don't have an intermittent problem anymore. At lunch I stalled out at a major traffic light on a 3 lane road. The car just stalled...so, all freaked out and starting to sweat, I tried and tried to start the car. It would fire and then stall....hmmm sounds tachometric. Car fires up all of a sudden, rev to 6800rpm....make it to next light then stall out again. I'm now in the left turn lane with my hazards on and the engine cover up!

While I'm in the middle of the road, since I have a spare tachometric relay in my tool kit, I unscrew the fuse box and swap out the relay.....jump in and start....fires up! I'm outta here!!. I get back to my house...get it in the garage and....out like a light! This time, it will not start....just the typical start up, fires for a second then dies.

Now that the problem is no longer intermittent, I can now look for it. First, get online and get archive info on tachometric diagnosis ( again! ) Boy, Steve Magnesson is the man....even in the archives!

First, verify 12+ on violet on crank....OK

position on....12+ on blue wires on W connector...OK

Cranking.....12+ on thermoswitch.....OK

Clean all connectors on TDC and connectors under coolant tank...OK

Clean connectors on starter solenoid...OK ( one of the wires goes back to the fusebox for fuel injection )

Still firing up, then stalling.

Tachometer moves while cranking and almost firing up....signal to tach...OK

Still fires up then dies.

New tests.

I pulled the tachometric relay and bypassed pins 30 & 87. Both fuel pumps running. Pull each fuel pump relay to verify both pumps working...ok. I crank up the engine and it fires on half the cylinders(Right bank CYL 1-6) ....Ah Ha ! .....Uh oh....now it seems coil related. I verify with my timing light and the left bank (7-12) is dead.

The left coil sends the tachometric relay some signal. If the module on the coil or the coil is bad, it won't fire up. I'll just fire up then die. OK, (getting excited ) I swap the module from the right coil to the left and vise versa. I plug in the tachometric relay and crank....IT FIRES UP !!!.....only on half the banks though. Since the module from the right coil was OK(now on left coil), it passed the signal to the tachometric relay and fired up the car. Obviously since the other module is bad ( now on the right bank ) it doesn't fire. I again verified with my timing light. Yess....spark on left bank, nothing on right....exact opposite before module swap.

Ok, gotta get a module.

Owww....Ferrari only sells it with the coil at $895.

But wait.....( post from another thread by James Patterson from Norwoods)

In my experience the highest probability for single bank ignition failure is the ignition module, Magneti Marelli BKL 3B. This is used on Testarossas and the 328's, at least 95% of bank down failures we repair are a failure of that part. I can't remember when I have replace a crank sensor on that vintage of Ferrari that was not caused by something striking it or a cabling issue, it is a magnetic sensor so they tend to last forever. Ferrari does not sell the module separate of the coil pack so that is why the parts cost is so high. You can buy the module from independent parts suppliers for around $145 retail. You can check the sensors with a scope and piece of metal to verify that they are failed, as well checking the coil with a ohm meter. The coil itself tend to have a low frequency of failure as well.

Glad your car is back on the road, best of luck.
__________________
Keepin' the ponies prancin'



Yes....just need the module Magneti Marelli BKL 3B. I saw it on T rutlands site for 154.95. I will call them tomorrow and verify. They only list a description and their own part number.

I'll keep you posted. But I think I got it. It would not start up at all till I swapped the modules. I guess it was just starting to go bad when I first posted and since has gone out completely.


Shamile

Freeze...Miami Vice !

Great Job Shamile!!!!

You really have to be great detective to track down issues like this. In finding this problem, you probably also fixed any future intermittent problems may creep up over time. I'm waiting on the edge of my seat to see how things turn out!

The Transpo/WAI part number is: XM631. This is a direct replacement for your Marelli unit. I'm not sure who the distributor is in your area..

Regards,
David