Lousy TR idle and some backfiring

I spent a lot of time last year identifying electrical gremlins and fixed the poor start issue. It now starts well but the idle is still poor. I have not adjusted any of the fuel system other than replacement injectors and filters. I also confirmed spark on both banks.
However, here is how it sounds as of last weekend upon a cold start. There are numerous backfires audible in the exhaust.




I am still having an issue with pressing the accelerator after start leading to bogging of the engine initially rather than an increase in rpm's. I have to feather it and then push incrementally, back and forth, until the revs jump and I can hold it higher to get it to stabilize around 2000rpm to give it some life. If I push the pedal, the revs drop, then will suddenly, a few seconds later, will jump.
I would like to find someone with the Bosch expertise to stop by to check it out but otherwise I am not sure where to focus.
Thoughts?

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have a look right of the engine. there is a black box and inside a fuse on a relais. I think that this fuse is blown.
I once put this fuse outside this black box. Image Unavailable, Please Login Image Unavailable, Please Login

 

Thanks for the reply. That relay was replaced at the end of last year as part of the electrical gremlins. I will check the fuse again but I would hope that wouldnt be the cause.

 

Easy access, OEM look. Its even on sale!


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You can do a functional measurement of the protection relay system without disassembling anything by just measuring the voltage on the red wire at the water thermoswitch:

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If not +12V when the engine is running (or in the special test mode), unplug and replug the two round connectors on the black box (to wipe the contacts). If the red wire is still not +12V, then you'll need to get inside the black box to determine whether blown fuse, bad protection relay, or bad input signals at the protection relay (give a shout if you need information about this).

If you do have +12V on the red wire, but still the same symptom = not good...

 

both sides firing?

 

I havent done it this week but spent a lot of time on it late last year. Thanks for the reminders Steve, your last help got me through the pre-winter electrical gremlins.
I feel its now more of a fuel related issue.

And yes, both sides are firing..

I will recheck the switch in a bit and report back.

 

Red wire is +12v at start.

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Then no need to worry about anything related to the protection relay system -- it's working (even if you have some other problem).

 

I just checked the wires on the 1-6 bank and it could be the issue. I checked them last about 8 mo ago.
Center pin to coil end 612kOhm
Cap pin 6 to wire end 1.2kohm
Same for 5 and 4
Cap pin 3 to wire end is 1.5kOhm
Cap pin 2 to wire end is 5.2kOhm
Cap pin 1 to wire end is 15kOhm

I think its time for new wires....



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What are the best options for non-bank breaking wires? And perhaps just beginning with the ones that are way off.

 

You can always try trimming and repiercing your existing wires (at the distributor cap) as a test to see if the resistances get more reasonable (i.e., something like 700 Ohms per foot).

 

Good point. I will try that. If I resolve this and there is still an issue where would you head next?

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The diagnostic steps (in this order based on the cost/hassle of each) that I use for KE-Jet with Lambda systems is:

1. Confirm/deny all electrical components are working by measurement (for US KE-Jet with Lambda systems, this includes the tests of Diagnosis Sheet N. 6)

2. Confirm/deny basic pressure parameters by measurement -- regulated supply pressure, fuel delivery rate of pump when at pressure, lower chamber pressure, return fuel flow rate from fuel distributor lower chamber to tank (this confirms the orifice at the outlet of the lower chamber is not blocked).

3. Confirm/deny fuel distributor performance by measurement (equal flow rate -- i.e., equal volume delivered in equal time from all injectors with the airflow plate in idle, mid, and WOT positions) -- the "dixie cup test":

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Pass 1 and 2, but fail test 3 = call Larry F. for a fuel distributor rebuild.

I hope that fixing your spark plugs wires solves the trouble

 

Wires etc can be found here:

https://www.ferrarichat.com/forum/threads/ignition-wires.592338/

 

I hate those resistent wires and mostly replace them ( not only at ferrari, also on all other cars, mostly opel and the france cars ) when they make problems with wires with copper-wire inside and a resistance of 1 or 5 K ohm between the igniton coil and the distributor cap or with 1 or 5 K ohm sparkplug connectors ( not working on BB or TR, too short from the length )from bosch

 

Steve,
I took your advice and retipped the wire going into the distributor cap.
I notice that I have some emerging cracks in the plastic.
The results on the wires was very positive.
All are now between 750-1450kOhm except #2 which I realized is a different wire than the rest. The rest appear to be original. The #2 lead must have been replaced by the PO and it shows a much higher resistance, at 5.2kOhm.
What are your thoughts on the impact of this oddball? Its not because the wire has degraded, it clearly has different numbers and markings on it.

 

IME, the contact between the piercing point of the screw and the spiral conductor in the wire is the weak point in the whole chain so your improved result doesn't surprise me (and the silicone outer tubing is pretty effective at keeping the wire in good shape -- so doing a couple/few "repiercings" before replacing the wires should be expected).

Not great, but not a disaster -- don't see how it would cause a serious operational problem.

Here are a couple of the Diagnosis Sheet N. 6 tests that you can easily make at the unplugged injection ECU connectors:

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TR EM Pressure Actuactor Coil Resistance 20.2 Ohms. and 20.0 Ohms
TR Coolant Thermistor 1.921 kOhms and 1.955 kOhms

Both are perfect. This was a big part of my pre-winter exercise to cure the non-start issues.

Diagnostic test #2 needs to be done but I dont have the tools to do it yet. Do you have instructions on those?

 

Agree. Sounds like your running on 1 bank. Check exhaust temps on both sides. I had the same symptoms when a fuel pump went out.

 

No (just what's in the TR WSM).

 

I definitely have spark on both sides but do believe its more fuel related as well.
Where is the best place to take the temp and what should it read ideally? Is a laser temp sufficient?

 

laser temp both headers... or if brave touch with your hands. One of mine was ice cold...

 

I took the excellent advice on these forums and used the 7mm wire from these guys. Fit flawlessly back inside of my stock gear, cost less than $100 for all 14 wires and was done in a few hours. I checked my resistance and were all perfect when I reinstalled. Just a suggestion. I chased a dead bank of cylinders for a week only to find a sketchy coil wire. Not a bad investment regardless if it is your primary issue or not IMHO.

http://www.kingsbornewires.com/

 

Thanks guys. I ordered some of the Kingsborne just now.
My reinstallation from tidying up the wires provided a slightly better idle but not enough to say it solved the problem.