Understanding my 3.5 V8 EFI

Hi all,

Putting my quarter tank starvation problem to one side at the moment, I would like to understand my V8 EFI a bit better now. Partly cause I ran it all day today and gave it some serious work with a large trailer and about 1.5 metric Tonnes on top.

At the end of the tow somone remarked it seemed and smelled to run a bit rich. True, probably, cause I felt it wasn't giving all the power. And starting it after a run like that is difficult.

So the symptoms are: Not used or cold and no load it runs smooth and fine doing about 2800 rpm/70mph cruising lovely. But after a longer run starting is more difficult (5 sec cracking iso 2), and after serious use starting is even more difficult (10 sec). It splutters a bit and takes a while (10 sec) to run properly. Saying that, cruised it again at the end of the day 2800rpm/70mph nicely. ( no load)

With old carb cars a screwdriver can solve the prob. How is that with this 3.5 EFI ?

My Q is: From searches it seems these engines can run different when hot. How ? Can I trim it and how ?

Thanks again,

Have a look at some of the posts on MAF trimming....you'll need a digi volt meter. I just went through this and got it sorted. Any problems and give me a PM and I'll help you through it.

forgot this:

http://www.landyzone.co.uk/lz/f10/rangie-romped-mot-except-230328.html

Yeah mine was sometimes a bit reluctant to fire when hot.

It did, but it took a little longer.

I guess this is because the Efi system was leaner running when hot but the RV8 likes a nice rich start.

Not sure if 14cux has a feature for startup enrichment.

Regards the smell, yep, mine ABSOLUTELY STINKS. Makes your eyes water in the workshop within minutes.

Was the same on 14cux as it is now on MS and now I KNOW the mixture is good.

Have a read of:

Rover 14CUX Hot Wire Mass Flow EFI: Service and Troubleshooting

Super helpful and informative site that will get you da knowledge!

I kept my 14cux in fine fettle and it was excellent to be honest

Plenty of study material.

Thanks.

Need to find out which system I have, but no doubt a parts supplier can tell me.

Post up some pics of your engine bay, plenty of knowledge on here

3.5 flap type use a cold start injector on side of plenum its controlled by temp sensor which can often fail

My V8i

The MAF ?

'tis indeed. See... you're learning already.

Another

Is this a Rover hot-wire ?

Also from what I understand engine temp (coolant) is important for a proper working EFI. Does this mean that use of the correct coolant and quantity is important, or is it not that sensitive ? The Haynes Manual is not very specific.

The important thing is the coolant temp thermistor. If it's jiggered then the ECU doesn't know the correct air/fuel mix.

Did you say what year your vehicle is? Anyway it's known as Rover Hotwire / Lucas Hotwire or Hitachi Hot.

lorri789 said:

did you say what year your vehicle is?

Click to expand...

1991

Thank god it's a Hotwire!

The flapper systems were a bit poo

Using that website I posted up you can check every component with a multimeter. It's quite good fun and helps you understand the system a lot better too

An easy test, get a multi meter and test the temp sensor that's in the inlet manifold behind the dizy, if it reads a resistance of some sort (about 5k or something I forget), its ok. but if it reads no resistance(open circuit), its fubar!
on the right in this pic
http://www.megasquirt-v8.co.uk/images/optional/Thermostat Replacement Kit fitted_L.jpg

The resistance also needs to change linearly with temperature.

I recommend a dial type multimeter for most automotive tasks

Mine seems to run better cold than hot.

Will check the temp sensor.

Do these sensors either work or not, or can they also be in-accurate ? I was quoted £12 for a new one.

Worth doing ?

FlyingDutchman said:

Mine seems to run better cold than hot.

Will check the temp sensor.

Do these sensors either work or not, or can they also be in-accurate ? I was quoted £12 for a new one.

Worth doing ?

Click to expand...

with your symptoms and the fact its a very common problem its first thing id do

Yeah it's well worth it just try to fit a decent one, fool parts is the choice of nige at megasquirt