A

ajsphead

New Member
Am just sorting out the snags having finished my flapper to 14CU conversion. Everything fired up fine with a good cold start and cold idle, but no hot start and no hot idle. It's a 14CU not CUX, so running open loop. It was running rich so reduced the MAF to read 1.12V and was just about to set the base idle. I had to keep it running on the throttle butterfly despite having tweaked the little adjuster screw to stop it from stalling, this just made it idle hot for about 5 secs before stalling, so was going to check the ICV despite having cleaned and lubricated it.

Anyway, it stalled and predictably would not restart. I waited for it to go completely cold to commence the process again and now it won't start at all. I get turn turn turn turn catch turn turn turn turn catch turn turn turn turn catch etc.(say it quick enough and you get the idea).

The CTS is new, I took out the TPS to check it but can't manage to read voltage in position. Got a resistance reading of 0.22 to 4.8 Ohms, but it didn't always go back to the same point when snapping back shut. Variation of 0.17 to 0.23 Ohms so don't know if this is enough to affect the hot idle.

I've re-primed the fuel line just to be sure and have good flow pre and post regulator. The line is well away from the exhaust so shouldn't be subject to vapourisation. I have a stream of spark at the king lead and I haven't touched the timing. If I disconnect the MAF it makes no difference and I've tried returning the gain back to where it was to start with (2.2V and a lot of black smuts)

All the vacuum lines are on tight and everything is bolted down to specified torques.

So why won't it go.

Anthony
 
If you still have the cold start injector plumbed in try disconnecting it. Just take off the small wiring plug on the end of it.
 
The turn turn catch thing i used to get whenever the engine got flooded, once down to me turning it over, once down to the timing going bad and me not checking it.

Go through all the basics. Then go through all the sensors (which you are doing anyway)

Does 14CU self learn the TPS like CUX, ie the base value does not need to be set because it works it out itself?

Worth checking the TPS from the ECU pins anyway, then operate throttle and see how that responds, should go back to same value, my point is it doesn't matter what that value is.
 
Cheers. Will start with the plugs. As it was running so rich to start with, I reckon that's a good shout.

I did a complete change over including plenum so everything is 14CU from the valley gasket up. 14CU throttle pot has screw holes not slots so reckon it must be self adapting.

Hopefully that should just leave me with the hot idle issue.
 
Hi I run a 14 CUX hotwire system and I've heard of people having problems such as this, apparently when the ecu water temperature sensor fails it can lead to over fueling when hot and you end up with a poor running engine.
The sensor if its in the same place as a hotwire manifold is located between the distributor and throttle assembly, where the water exits the right hand head and goes to the thermostat.
This senses whether the engine is hot or cold and richens the mixture accordingly, so if this fails it will continue to overfuel when hot.
you can test the resistance with a good voltmeter and see if it changes between hot and cold, if not replace with a new part and this could cure it.
 
OK, next instalment. it was fouled plugs, all cleaned off and fine. So, we have the basic problem of no post start up map idle or restart. The idle holds for about 5 secs then dies. The hotter the engine gets, the loopier the idle gets, anywhere from 500 to 1500, settling after a bit to about 700 then dying.

The restart is trying to catch but you can smell it overfuelling.

CTS checked & within parameters
FTS checked & within parameters
TPS checked & within parameters
FPR checked & OK
MAF set to 1 Volt.
No speed sensor input.

I'm just left with the inescapable fact that you can't run a 3.5 high compression engine off a 3.9 ECU. Please correct me if I'm wrong.

I was planning to get it up an running on the 14CU then convert to MS when the pennies allowed, so I'd rather do that if possible.

All reasonable suggestions considered to get this one going as the head gasket has just blown on my P38 too.
 
When I've accidentally left a speed sensors unplugged in the past it's made the car idle way to high. Might be worth fitting a speed sensor. Or if it's an auto check you've got a gear select input going to your ecu. That can cause similiar.
 
Cheers.

Went out and played this morning. Problem identified.

Took voltages across R/B & U/G wires. 0.5V with ignition on rising to 2.1V at idle. About right for an 8 litre engine.

So the MAF is duff. Do I get a known good replacement or just go for MS now?
 
If you're fitting megasquirt eventually anyway, why waste any of that money on buying a new MAF now?
 
MAF it is then.

A correctly tuned 14CU(X) system is actually a great injection system to use. Very reliable and adapts to most circumstances.

Megasquirt is great for power and economy, but a bit of a pain to set up and if it goes wrong in the field youre a genuine breakdown - lucas injection system will keep running with most sensors disabled!
 
I've talked long and hard with Mark Adams and I'm going to get the hotwire running right. I've fitted a replacement MAF from a Jag XJ40 and now everything is working within parameters.

I now have a hot idle but

1. The idle sits at 550 or so and no adjustment of the bypass screw makes any difference. It will rise to about 800 if I blip it, but after 4 or 5 secs it drops back down again.
I'm tempted to blame the ICV but it's as clean as a new pin inside and well lubricated. On shut off I can hear it retracting correctly, so I'm not so sure.

2. I also still have no hot restart. With a correct MAF I can't smell it overfuelling either.

3. What may be related is that I now have a howl coming out of the air intake at low revs and idle. It's pretty loud and the pitch rises as you increase the revs then it disappears past about 1200.

Logic tells me it's an air leak into the inlet tract somewhere, but I've no experience of this so would continue to appreciate your wisdom.

It's beginning to bug me now.

Thanks
 
The idle screw should make a difference. You need to block off the hose to the idle control valse to set base idle though. that hose runs to the just by the back of the idle control screw area to the idle control valve hosing it isnt split or broken is it, same goes for the fuel pressure regulator hose?!

With the engine running try squirting a can of carb cleaner around the engine, if it eat drawn in by an air leak then the idle speed will rise
 
Cheers, I'm confident the head gaskets are fine, or at least they were when I took it off the road to do the job. Should also say that the coil does not get hot and the fuel lines are routed well away from heat sources, so I ruled them out quite quickly.

What do you reckon about the howl?
 
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