Engine Dies 1 sec After Start

[blichjr]

Just replaced the turbo and muffler on an 89 930. I turn the key and it fires up instantly but dies after a second or two. Oil pressure registers and the oil light goes out. What could be the issue? Did I bump a relay, inadvertently disconnect a wire? All hoses seem to be connected correctly.

What electronic or other component would kill the engine??

[Porboynz]

While not familiar with the 930 turbo the basics are fuel and spark, so which is missing? Sounds like fuel to me, maybe the cold start fuel injection is enough to start and then, nothing.

[blichjr]

Thanks Porboynz! Sorry for the newbie question but how does the engine get fuel just for the first few seconds?

[al lkosmal]

I am not a turbo engine expert, but on the NA CIS system.....Typically, the cold start injector provides the initial fuel to get the engine started. Once started the air-flow paddle lifts, activating the piston/plunger in the fuel distributor and then the fuel distributor provides fuel to the injectors.

It sounds like you may be getting the initial cold-start injector fuel....and then nothing. There are standard system pressure tests that may need to be done, but I would start with checking to make sure that the air flow paddle can move freely.

[SpyderMike]

The DME Relay explained - Dorkiphus.net

[timmy2]

Over boost sender working correctly?

[blichjr]

OK - I have the Bentley manual for up to 89 Carerra but it doesn't include the Turbo model. I ready through the detailed DME in that manual and also the link by SpyderMike. Understand the system much better but damned if I can't find the location of the DME relays. On the Carerra it says under the driver seat. That is where the ECM is located, and a couple other large relays but none of the pin-outs and part numbers refer to the DME/Fuel relay.

Timmy2 - how is the overboost sensor checked? Again - not in the Bentley manual. Location of that sender??

THanks guys! ANxious to get this new muffler and turbo out for a run!

[javadog]

You don't have a DME system, so there's no DME relay, so quit looking for it.

JR

[Rodsrsr]

930 doesnt have a DME relay. Those are only used on the motronic cars. Beat me to it. lol.

[javadog]

I neglected to mention that you should sell the Bentley manual and get some of your money back. It's more or less useless for your car.

JR

[blichjr]

Any idea where to find this info for the '89 930? What type of ignition system DOES it have then? Any thoughts on what might be going on and what to look for? I've checked all hoses and wiring again and it doesn't look like I bumped or missed anything.

What things in this system would let it have fuel and spark to start but cut it after a sec?

Probably unrelated because it's been doing this for 9 months but when I open either passenger or driver door the horn honks for just a sec. Not the little inside buzzer - it's the horn in the front. It also gives a honk when I turn the key. I've replaced the door switches but it still does it. Just a quick honk.

[blichjr]

Out of curiosity I looked under the passenger seat and there is a black box maybe 1" tall, 6X6 and has a heat sink in the back of it. I am assuming it is some after market stereo component, but it looks to have factory mounts on it welded to the floor of the car. Couple dangling wire connectors too in the front. Without removing the seat I can't tell for sure what it is. Wires lead to the panel by the shifter best I can tell.

I also removed the EGR pipe from the catalytic converter (I took out the Cat when I installed the muffler) up to the valve where it enters the engine compartment. I plugged the hose. Tried with the plug in/out and no difference. That was about the only change I made other than the turbo and muffler.

[javadog]

Assuming the car ran fine prior to installing the turbo, it's reasonable to assume something you did during the install caused the problem. List everything you did to install the new parts, so we might guess what you want to look at.

There's no single book that you can buy for working on the 930. The Bentley is next to useless, for a variety of reasons. The documentation I used was comprised of:

Factory service manual set for the 911, up to 1983, 6 volumes
Factory additional service manual set for the turbo, 2 volumes
Factory additional service manual set for the 911, '84-on, 4 volumes?
Factory service training documents, some year-specific, others model/topic specific
Factory PET software
Factory technical specifications books
Factory service bulletins

Porsche's concept for documentation has always been to publish a basic manual set for the introduction of a model, then publish annual supplements that document the changes and new technology. It was designed for dealer use and not for the guy that wants to learn about his specific car 30 years later. Since so many incrememtal changes occurred over the years and many owners will offer advice based on what they know about their car, which may have nothing in common with your car, most attempts to shortcut the education/documentation will just frustrate you.

The ignition system on a 930 is similar to a 911 up through 1983. Nothing exotic about it.

There are a couple things unique to a 930, the overboost relay and the delayed cutoff relay. Apart from these, the injection system is similar to a pre-'84 911.

If you want the box under the seat identified, shoot a picture of it. Removing a seat is easy, takes less than 5 minutes.

JR

[javadog]

Forgot a couple things. As for your horn issue, which is one of the more bizzare things I've heard about, you need to take a look at your wiring for evidence of tampering by a previous owner/idiot. I'd look at the fuse box area and the ignition switch area.

Did you remove your intercooler when making the recent changes? If so, did you plug the wires to the boost gauge sender and overboost switch into the correct places?

JR

[blichjr]

Javadog - thanks much for the fast replies. I'm working on the car today! OK - so I pretty much have the old CIS type system then? That explains the adjustable distributor then. (I think)

YES - I removed the intercooler, but I don't recall removing any wires. At least not on purpose! I took it off again this AM and looked for pinched o-ring, missing hoses etc. and there was nothing I could see missing. The only hoses I removed were the one going to the warm up regulator and the one going to the wastegate. Of course there are the o-ring sealed inlet and outlet connections. There are no wiring connections to the intercooler right?

I didn't have the rear fuse panel cover off, but looked at that today.

I do think there is some idiot wiring from the previous owner with a fancy ass satellite stereo system. But I've not had issues starting with the car before. The horn thing started up about 9 months ago and I hadn't taken time to hunt down that problem.

Overboost relay - wouldn't that only come into play in an overboost situation?
Delayed cutoff relay - wouldn't that only come into play when you turn the car off?

Where did you locate the documents you referenced? Would love to get my hands on some.

[javadog]

Originally Posted by blichjr

Javadog - thanks much for the fast replies. I'm working on the car today! OK - so I pretty much have the old CIS type system then? That explains the adjustable distributor then. (I think)

Yes, you have a CIS system but the distributor isn't part of it. It is a basic distributor that is like the ones that preceded it.

Originally Posted by blichjr

YES - I removed the intercooler, but I don't recall removing any wires. At least not on purpose! I took it off again this AM and looked for pinched o-ring, missing hoses etc. and there was nothing I could see missing. The only hoses I removed were the one going to the warm up regulator and the one going to the wastegate. Of course there are the o-ring sealed inlet and outlet connections. There are no wiring connections to the intercooler, right?

Nope, wrong. You have wires going to the overboost switch and boost gauge sending unit.

Originally Posted by blichjr

Overboost relay - wouldn't that only come into play in an overboost situation?

Nope, again. You need a ground on that part of the circuit. See the photo below. Make sure a white wire is attached to the overboost switch (left side of the photo.)

[javadog]

Originally Posted by blichjr

Where did you locate the documents you referenced? Would love to get my hands on some.

I bought the service manuals and technical spec books new, through the Porsche dealer network. Pelican should be able to still sell these.

PET is available for download, free from Porsche.

Once upon a time, there were bound volumes of the service bulletins available from Porsche. I have no idea if they still sell them. I seem to recall that they were published by PCNA after they took over from VWOA. There are probably parts bulletins, too, but I've never acquired any of those.

The service training books werre purchased used, one at a time, from eBay and other sources.

Some of this stuff comes up for sale from time to time on the used market. I've sold off most of my collection; others do so from time to time.

There may be bootleg digital copies of some of this out there, but I'm not a fan of copyright infringement, so I don't use them.

JR

[blichjr]

I took a look at the rear relay / fuse panel again and one fuse was blown. The red one in the middle. I replaced it but it didn't make a difference. The bottom fuse is missing and doesn't appear to have anything connected to it anyway. The upper fuse was fine. I replaced the middle fuse and it didn't make a difference. Looks like the middle fuse wire is a bit dark where it goes into the panel. Not sure if that is just grease/age or a burned wire. Hate to tear into that if it isn't related to the trouble I'm having.

[javadog]

Forget the rear fuse panel for the moment and look at the wires under your intercooler.

Make sure you have a white wire attached to the overboost switch.
If not, connect the wire and try starting the car.
If so, remove the wire, connect it to a good ground and try starting the car.
At the risk of repeating myself, make sure the white wire is not attached to the boost gauge sending unit by mistake. It's possible to swap the two wires.

JR

[blichjr]

Do you have an aftermarket intercooler?? Mine is the original - just did a check and both of those components are connected to the large black valve housing, not the intercooler itself. I can pull the intercooler off again and send some pics.