Philip88

Hey guys, I recently purchased a 84 928s. However she does not want to start when the engine is warm. But starts on the first turn when cold and runs smoothly but the idling is inconsistent when she heats up. I saw the MAF sensor is not plugged in and cant find the relevant wire, can this be the reason for the no start when hot?

davek9

Please tell us a little bit more about your car, is it US or European?
And yes, short answer the MAF needs to be plugged in for a car equipped w/ one to run correctly.

Philip88

I'm still new on here will fill my profile as I go. It is an European. Only got it about a week ago. Suspension feels solid paint and body is very good. Interior wise all the buttons and ***** work, carpets and seats are still good however the dash is cracked a bit. The auto also kicks over smoothly when driven normally.
Some of the window rubbers seem to leak a bit so will probably replace those.
It has 206000km on the clock.
Only mods I can see on the engine is they moved the distributor, and then the MAF sensor that doe not have a connection.

I know the MAF is essential so will fix this (for whatever reason the previous owner unplugged it, maybe a faulty MAF?) but can the unplugged MAF be the culprit for the car not starting when the engine is warm?

Mrmerlin

I would suggest to replace the green wire (goes from the hot post area to the distributor) as well as the spark plug wires,
also inspect the vacuum lines to the fuel dampers if you smell gas then they are ready to be replaced

Philip88

Thanks any form of advise is appreciated. I usually perform most of the work on my cars myself with the occasional aid of my dad. I am awestruck by the engineering and built quality of this car (it being 30 yo), which in a certain sense makes me extremely cautious of just stripping.

I have been smelling fuel while the motor is running and have been meaning to replace all the rubber fuel lines. I also want to replace the timing belt just for in-case and then some new plugs, oil and filters. But first I need to fix this hot start issue and sort out the MAF.

Mrmerlin

Ahh first you need to find out where the fuel smell is coming from and fix it, otherwise it could go up in smoke,
from the pictures your car looks like it is the version prior to the early MAF version.
THUS it doesnt have a MAF .
NOTE the early MAF version also has a dual distributor

davek9

What did you mean by ".. They moved the distributor.."?
I see plug wires going down by the fan, also remove that plastic cowl cover (over the windshield wiper mechanism) its held in place by that rubber seal, else it will be destroyed when the wipers are used.
It needs to be installed directly in the tabs under the cowl.

Great looking car, like the two tone interior.

Philip88

Yes I am planning on running over the whole fuel supply system to find out where the smell is coming from. I can see the rubber pipes that goes into the injectors are cracked and some of them are already replaced so will probably start there.
Whats the difference between the pre-MAF system and the normal system? How will I be able to tell the difference?
I will be attaching some more pics I just took of the MAF.

Also see the pics for the distributor. I do not really like the way it looks now so will probably try and change it back to the old system. The previous owner said the guy who had it before him installed the current distributor. Also thanks for the advise on the cover.

Thanks I also like the interior, thinking of having the dash redone in vinyl.

123

You're in for a surprise. I'll let someone else tell you.

Wisconsin Joe

Yeah. Someone got...

Umm....

Creative. That's it.

First off, if you can smell raw gasoline (petrol) in the engine compartment DO NOT drive the car. Period. Not to the shop, not "just a little." Not at ALL. Too many people have watched their cars go up in flames because they thought that the fuel leak was "only a little bit."

Your car looks like an 84 "Euro" (non-US version). That's interesting. Because if it is, you do have a MAF, and you should have the twin distributor setup. 2 distributors front to back on the bare rotor on the front of the motor.

You have what looks like a pair of 32v dizzys mounted near the fan. I'd love to know how they are driven and what they are mounted to. Perhaps the original dual drive. Wow.

If you look on the top front of the motor, you should see the engine number. If I'm right, it's going to be M28 something.

If you post the VIN, there are folks on here who will tell you how the car was originally made (delivery country, motor, trans, options).

Here is a post of my engine. This is what a 4.7 Euro "Twin Dizzy" looks like:

https://rennlist.com/forums/10205813-post27.html

davek9

Wow, that's some kind of after market or "adapted" electronics ignition system.

I would suggest you put it back to stock as making the current system work w/o knowledge could be painfully $ and frustrating. We can assist w/ putting it back to stock.
sorry id only be stabbing at help w/ that setup, someone else my know.

Dave

Mrmerlin

Well thats gotta be a first ...
from the pictures you have a Frankenstein modification.
It would be a good idea to talk to the PO and see if they can supply info on all of the mods that have been performed

Z

Those are not 32v distributors. They're two coil packs from... something other than a 928, and probably not even a Porsche.

No, not really. Somebody apparently installed an aftermarket engine management system in the car, or possibly one from some other kind of car. An older style single distributor was modified to work as a cam position sensor. I see a stock looking 928 MAF, but it's not doing anything as far as running the fuel injection, since it's not connected electrically. In the picture, the end of the MAF that the air is supposed to flow out of isn't connected to anything, and the picture doesn't show what's connected to the opposite end of the MAF. It's probably a MAP sensor based system of some kind. I'm only seeing a big empty space where the stock air filter and air entrance into the intake manifold is supposed to be, so there's no telling what's going on there. The same goes for the throttle body. I'm not seeing a crank position sensor. Maybe the one from a stock 928 is being used, maybe not. The same goes for a toothed wheel.

If you look under the carpeted panel at the side of the passenger footwell, and also the fuse panel, I'm guessing that you'll find even more surprises and things to keep you or your mechanic busy for a while.

Philip88

Not really liking what I am reading.

The thing is if I understand correctly the car should go into Limp mode without the MAF? It does not, it is still mind blowing fast.

Do you think the PO changed more than just the distributor?

Unfortunately I could not get the contact details of the person who originally had the car when all of these conversions were made.

Thanks for the advice on not driving it with the current fuel leak. I have also read some horror stories of them going up in flames so not planning on driving it.

As mentioned prior I only bought the car a week or two ago so drove it home from the previous owner and twice around the block. First want to sort out the kinks and give it a full service, so will do the fuel lines also.

The relays and fuses all still look standard. That was the first place I looked when it did not want to start. But the original LH unit looks different.

Think I will probably take it to a guy who can run a diagnostic. Luckily a friend of my dad specialized in VW and Audi diagnostics back when they first started coming out with computers so hopefully he can give me some pointers.

Hilton

Your car is no longer running the stock ECU - or at least, the stock ignition ECU. The PO definitely changed a lot more than just the distributor Being an '84 model from outside North America, it had LH2.2 fuel ecu, and EZ-F ignition ecu. Judging by the twin coil packs, you at least have aftermarket ignition. Whether you've got aftermarket fuelling too remains to be seen.

Your first task should be to work out what system is on the car.. so first step should be to examine the ECU's in the passenger footwell, and figure out which ones don't have a Porsche part number. Everything factory *will* have a Porsche part no, like the ABS, bulb control module, etc. Following the wires from the big rubber boot that comes through the firewall at the top left of the electric panel should lead you to the ECU, as thats the injector and engine harness. Unscrewing the elec panel from its bracket so you can lean it forwards will make it easier too (disconnect the battery before moving it all around, at least until you've checked out the wiring).

Given the car runs well, it may be sensible just to maintain it as-is, but knowing what you've got will help in that process.. whether its Megasquirt, Haltech, or any number of other possible aftermarket/homebrew solutions.

Post some pictures of the wiring in the passenger footwell - also look above the passenger parcel shelf, and also in the outside corner under the dash as there's space there to hide an ECU too (around to the left of the glovebox in an RHD car - above where the heater hose is that pipes air to the passenger door).

Once you know what you've got, you can figure out which components its using.

Aftermarket ecu isn't a bad thing - several people have changed to it on these forums for benefits - it just makes it a challenge to figure out if you're not the guy who did the work or had it done.