Need Help, Running Rich on Right Bank.

Very early on, this car had other issues and wasn't even firing on 3 of the 6 cylinders on the 1-6 bank. New sparkplugs fixed the firing, but we checked the cap, rotor, wires and connectors and found no discrepancy. I forget what the resistances were, but maybe we'll check again. We did clean the electrodes inside the cap, and the end of the rotor when we had it apart. There was a small amount of carbon on some surfaces.

 

Hi,

How did you get the current at the EHA ? it is a nightmare to reach the plugs on the EHA boxes..

 

it is not a nightmare - if you have the right tools, the wiring diagram and a little knowledge you can do this. also you may remove some parts and you can unplug.

 

From the right side I was able to reach my hand past the intake, between the cross over pipe, and then wedge my elbow in under the coachwork. I then unplugged it, and Sleestak made up some jumper wires to plug into the EHA connector and onto the EHA plugs.

We placed them, and then I un-stuck my arm and we took the current measurement in-series.

 

Job well done...

I've been learning while following this thread - THANKS!

You measured the resistance with a warm engine. Can the CTS be tested while the engine is out of the car in a 'cold' condition? I'm thinking it might be an easy check to do as 'routine' during an engine service. Might catch it early.....

Presumably when you say "Swapped it" you actually mean "Replaced it" (the CTS).... please confirm.

Any idea what NTC stands for?

For those who are also trying to follow the thread, I've included a pic of the offending wiring diagrram to show the 'dual channel' (#13 NTC) that you had described.

Thanks again for sharing!

Rgds,
Vincenzo
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Negative Temperature Coefficient (it means that the resistance of the sensor goes down as the temperature goes up).

Here's how to measure the resistance of the sensor at each of the unplugged injection ecus:

http://www.ferrarichat.com/forum/139830738-post3.html

 

What Steve said.

Funny thing is, when we first searched "NTC", most of the literature had to do with thermocouples, so we ignored that thinking they were the EGT (exhaust gas temperature) sensors in the exhaust and that the imbalance might be due to one side misfiring while the other wasn't. It was only later in the day, while trying to search what Ferrari meant by 'NTC' that I found a reference to it here on FC (it was actually Steve's post linked above) and the lightbulb went off (on?).

Yes, when I say swapped, I mean it was replaced with a new sensor. The bosch part number was cross referenced at autozone by a very helpful commercial sales person who actually knows what she's doing (versus the typical tuner-driving red shirt that isn't sure what a part number is).

If you follow Steve's post, you'll see the chart which shows resistance vs temperature. If measured at cold only, it might not show as bad. Though both channels should measure closely to one another (some deviation is expected). One trick might be to measure cold (note the ambient air temperature) and then use a tea kettle or boiling water to heat the sensor body and re-check the resistance. While not precise, a misbehaving sensor should show trouble.

The connectors for the coolant sensors are directly under the grille ahead of the 'hood', which leaves them subject to water intrusion. Liberal application of dielectric grease should help avoid corrosion issues within the plug and sensor. The sensor we removed showed copious corrosion on the leads. We did not attempt to fix the leads to save the sensor (At ~$30, there was no reason to attempt to save the original).

Now to figure out why it hits that invisible wall at 5k rpm.

 

You had to see this question coming: What is the cross referenced part No.?

Thanks to everybody - FChat beats a textbook by far!

You can bet that the experts on this site are some of the best - if not THE best at understanding and diagnosing the TR!

Next time I pull the engine, I'll break out the tea kettle (and the NTC thingy;-).

We eargerly await episode 2: "that invisible wall"

Hats off!
Vincenzo

 

Steve's other thread has the PN listed in the picture showing the 2 channel NTC.

 

Thanks again!

 

Are you sure that your tachmeter is working properly?

 

Yes, at least reasonably well. Using a timing light with RPM readout, the tach agrees with the timing light.

 

Can't recall any other prior reports of this symptom on a TR (since TR don't have the things on other models that usually cause this - mis-set rotor-to-cap, bad mechanical advance, points not right, etc.). Have you had a simple look inside both distributor caps just to check for something obviously wonky there, or put a timing light on it to see if the ignition pulses go missing when the problem occurs?

On the fuel side, the fuel pump fuel delivery test in the TR WSM might be useful to check -- just a thought...

 

That's what we'd planned to do, timing light and maybe fuel delivery check (though the though of playing with fuel splashing everywhere does not sound the least bit fun, though it seems the answer always lies in the jobs we least look forward to).

Sleestak hasn't driven it enough yet to see if it's a permanent problem, or if we think it's spark or fuel delivery. On the trip back from the smog shop, the behavior seemed to have 'corrected' itself, which I find worrying.

That said, the car had 3 fouled plugs on the 1-6 bank when we first started. They looked good (not too black, no build-up) but the timing light showed those cylinders dead. We swapped plugs around and the problem followed the plug. Replaced the plugs and that problem went away (and then it almost passed smog afterward. Idle it passed, 2500 rpm it failed).

I'm wondering if the plugs aren't questionable due to all the tinkering we did to get it fixed and are misbehaving at higher cylinder pressures. We'll either have to check for spark as it hits it, or just see if the problem goes away with some more mid-range miles on the engine. Now that it's smogged and registered, we can slowly chase down the culprit. There's a few other bugs (slight oil leak, headlight switch is busted, front bumper alignment, some hackery in the relay/fuse box area that needs to be reversed to OEM) that need to be worked out in the meantime as well.

I'm not very trusting of the aftermarket alarm that's been installed either, especially since it has a starter solenoid cutout. At random times, the starter will refuse to crank - jiggle the little bundle of hacked-in relays under the front hood, and presto: running testarossa. If it has any control over other relays in the car, then there might be a loose connection in that alarm somewhere causing the issue. I've seen iffy electrical connections pop in/out based on rpm due to vibrations, so we've got plenty of variables to check.