Was just driving down the highway thinking, damn this car is driving nice, and it was/is...

I got off the highway and am not sure what to do now. I hope folks are out there looking at the forum.

The car never completely stalled. Is still running. Turned on and off multiple times and she starts right back up.

Driving along at 60-65 and got this massive HICCUP. RPMs dropped, car felt like it was going to stall, started pulling to the shoulder and things "came back on line". Because I pressed into the throttle to raise RPMs, when things came back, the car downshifted into second, back into 3rd, RPMs settled like normal... Everything "normal". Started looking for the next exit, maybe 1.5 miles. Happened again, as bad, the same. Never stalled. Car and RPMs became irradic on the stall side of revs, way low, I pressed into the throttle and this came back, continued driving until I could stop and have a look see...

Pulled off the road and started looking. Pulled off and reset CTS,,, coil plugs,,, all HT leads are tight and in place,,, checked battery cables - tight,,, what I could of the fuel pump power lines - fuel pump running smoothly,,,, both relays in trunk, main and fuel pump,,, umm the amplifier connections and to the best of my ability, the link in the (+) battery cable... I don't know what else to do...

I just drove about 5 miles,,, sweltering heat today,,, back roads to make it to some kinda destination... Nooooo issues.

Listen, I am all ears. I hate to come off sounding like a crazy alarmist,,, but I have to get this car home now, about 15miles in very unforgiving NUC highway driving just to get her to base.... What could this be?
​​​​​​

 

Hi Jay

Perm any one from ten it could be anything!

It could be a Fuel Blockage or the Spinner in the Dizzy or maybe its the 'Uber Expensive' Crank Position Sensor, under the Front Pulley, that either needs adjusting or replacing and that is my First Guess! as well as being easy to Test, in the event that you happen to have your DVI Meter with you?

Just don't tell me you left that at Home!

Testing it is dead easy, just unplug the CPS under the Bonnet/Hood and having Set your Meter to Ohms, insert the DVI Meter Probes into the Plug and then Spin the Engine and see if it gives you a consistent reading

This should be only for a very quick Test, as if it needs to be longer, pull the Fuel Pump Relay so you are not Pumping Fuel

A Faulty or Badly Adjusted CPS can cause your Car to pull up at any Speed

'Ask me how I know' it happened to me!' and felt just like I had Switched off the Engine

If you need a New CPS send me a PM as I've got a Hack that could save you a Fortune that I did on my own Car the very same model as yours and She is running very fine and has 'Light Switch Ignition'

 

Trying to figure out MY and engine….

 

I think its a '90 V12

 

Marenelli failure?

 

I had a quirky problem on my 96 4.0. The car would stall out and start right back up. The car would run OK and then when I put my foot into a little it would sputter and feel like half of the cylinders had dropped out. It gave me a fit for a long time until I figured out it was the battery disconnect switch. It was the type with the knob you turn to make or break connection and it would momentarily break connection while the car was running. No problems since I removed the switch.

 

Generally sudden things like that, especialy the 'intermittent' behaviour are generally electrical in nature, hard to say where to start checking that out with any certainty, if it is running you may be able to reproduce by moving wires and such - beware HT leads they can bite but they can also be the problem especially the king leads to the coils - these are somewhat unlikely if it is a 'whole engine' death.

 

Did you have the AC on? If it happens again try turning it completely off and see if your power comes back. Then let it sit for few minutes.

My compressor got some sort of hydraulic lock the other day, only the second time I've known it to happen (on friend's Ford van last time). Acted Exactly as you describe. After turning off AC and parking to fill with gas, it righted itself in a few minutes (equalizing I guess) and all was well. Been well ever since.
(';')

 

Probably not the case, but could be fuel starvation due to blockage in the vapor trapping system Easy to test, just remove the fuel cap and try starting it.

 

You guys are ALL awesome and thank you for replying...! I mean it, really...

Crisis averted as it is... Crazy me

I continued into Brooklyn, picked up MeLady,,, we drove back to my place, about 15 miles and grabbed another vehicle to drive down the NJ Shore... Pls don't think I'm bragging or boasting when I say that,,, as I am REALLY beginning to feel like I can't keep up with all these damn cars. Anyways,,,

It's a 1990 v12. Yes, Marelli car...

As advised on this site,,, I should always have a DMM with me as well as a CPS. But I don't. I would love to know the CPS hack,,, everyone should... So if you don't mind, please share with all the good people here.

I have some "refreshing" to do with the connectors to my coils off the main loom. Dizzy and rotor are pretty new. Coils are new-ish. Front CPS was replaced 3 years ago. Rear one at the bottom of the bell should be replaced soon, now...

I have NO idea what this was today... Which kinda sucks. I'll go home and drive til it completely breaks down? It's like a needle in a haystack and unsettling enough not to plan a trip in the car til it's sorted. PITA

I want a new main relay and a one for the FP in the glove as spare.

AC was not on and the belt isn't strung on the pulley for now.

 

Could have been vapor lock since your A/C is not working and thus your return fuel cooler isn't working. If the tank was low on fuel, that would make the fuel get even hotter.

Jon

 

Was thinking that at first but when all this occured, I had been driving no more than 20min,,, highway, temp never came to N,,, which I'm very proud to say, it never does when on the highway - even on the hotest days... Tank was/is full...

I also wanna make an overall statement... This car, by FAR, is the favorite of any car I own and (cept when it doing this) it just keeps getting better. Such a lovely lovely machine... Jus say'n

 

Good Morning folks... I'm hoping for a little help.

I know I could comb over the forum and find answers but I got a list today. Took a day off. List is work on a 928, and XJS and an XK8... So,,, if someone can offer a SPEC for the front and rear crank and flywheel position sensors I would be super grateful...

Is there a right ohm's that I could look for?

Also want to move the ignition amps off of the rad cover plate. I've been looking at the headlight wells on the INSIDE of the bonnet. Split the, one left HL well, one right. There has to be a cooler place they can call home.

Then, rewire the SHAMEFUL job I did on the coil connectors. I have two new dorman female pigtails and I just want to solder them in right and then,,, see what happens. I'll also take a close look at the dreaded white wire WIIT...

So, right ohm's for the CPS and FPS?
Anyone?

 

Oh wow!

Have a new CPS right here to measure against...

Also, if anyone is out there listening to my madness, a RIGHT reading for the CTS as well...

I would appreciate it!

 

Well well.... What do we have here?

 

Looks like a major suspect in a failure investigation to me ....

-10 C = 9.2k ohm
0 C = 5.9k ohm
10 C = 3.7k ohm (50° F)
20 C = 2.5k ohm (68° F)
30 C = 1.7k ohm (86° F)
40 C = 1.18k ohm (104° F)
50 C = 840 ohm (122° F)
60 C = 600 ohm (140° F)
70 C = 435 ohm (158° F)
80 C = 325 ohm (176° F)
90 C = 250 ohm (194° F)
100 C = 191 ohm (212° F)

 

Ok! Thank you... I'm assuming this is the CTS...?
This is definitely with a temp between 90c and 80c or so. So looks good.

Damn car starts RIGHT up and idles smooth! Which sucks, lol...

Both front and rear Position Sensors warm/hot were at 745ohms... New one COLD was 675 ohm's...

TPS was dead on at .32 volts, car off ignition on. But the wires on the back of the red cylinder are looking ugly. I hate to say it.

CTS hot...

Three wires off the back of the TPS... One of them is exposed and looking a ratty brown. I didn't dare pull it out today.

 

For the ignition amps,,,, what if I added two washers UNDER the heat sink plates creating an air gap between the plate and the rad cover plate. Seems like that would aid in keeping the damn things cooler...? OR is my thinking, as happens sometimes,,, backwards on that? Does the cover plate help cooling, even though it get up to ah million degrees...?

 

Yes CTS sensor and by my calcs that puts you at around 86°C, sorry should have been more specific what the table was.

On the cooling your idea is good but I'd still pop the amps off the plates and put some fresh heatsink compound under them - I'm pretty sure the Marinelli is supposed to have it and it does degrade over time.

 

I hear ya, I'll do both...
I tested the CTS after idling the engine a while.

That wasn't the 12v lead to the coil connector but it was one of the (I dunno) leads. A signal lead of some sort I'm guessing. Haven't studied the ED yet. I replaced both connectors. These were some very generic connectors I found, I think on Amazon. The new ones are at least branded. Dorman connectors.

Like I was saying in earlier post, my last attempt at wiring them up was pretty shameful,,, and lazy... One of those things where if I found it like that I would have made a statement like - the PO was a hack - or something like that. I need to get my act together.

I hope this was the issue. If not, there's always AAA towing... And then, AA...lol, Alcoholics Anonymous hahaha