So 2 weekends ago I took the 914 out for a weekend drive. She was running great but on the way home the exhaust volume rose quickly and it started to sound like a loud lawnmower. I drove it 5 miles home and parked it till today.

She still starts and idles normal aside from the sound but when looking into the engine bay on the driver's side I noticed what looks like a backfire coming from a small hole just left of the air intake runner. I've attached a picture with an arrow pointing to the hole.

Anyone know what could be causing this?

Engine is a 2.0 fuel injected from a 74

Thanks in advance for any help or suggestions.

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That little hole in the head is for the EGR air injector. It goes right into the exhaust port above the exhaust valve and what was used to cap it off has come loose or failed in some way. All you need to do is find a way to cap it off again. Remember you're dealing with hot exhaust gasses under pressure. I capped mine with threaded metal plugs. If you can see threads in the hole you may be able to do the same. Good luck, Ray

x

I used 10mm valve adjust screws to plug them. I know they are 10mm x fine pitch (I think it is 1.00).

head is from a75/76. Engine# will tell you what year the case is from.

Looks and sounds like it used to have the plug in there, so look around in the engine bay for what was closing the hole up before. Better check the others also. Two per side.
here is a pic of mine. First the front one, then rear.
Tom

Thanks for the info guys. I seem to be missing all 4 of them. Is it normal not to have them in there? Did a gasket cover the hole and fail possibly?

As far as getting some bolts to plug the holes, I can get some 10mm fine thread like suggested above but is there a max length i shouldn't exceed?

Thanks again for all the replies! Your guys are super quick and helpful

Any idea how long those bolts are and where the threads start in the head?
I stuck a 3" long 10mm bolt down the hole but never hit and threads.

Yes, you have either '75 or '76 heads.

I blew one of those out of a '75 head too. Had a big old flame shooting out at me.

Looking around in the engine bay, I found a 1" long set-screw looking stud with an Allen tip sitting on the left engine shelf.

I reinstalled it with a dab of Loctite, then did the same to the other three. The threads start quite a ways down in the hole, so I used a long Allen wrench to tighten it up.

There are a few ways to plug the ports ... sounds like maybe you also have Allen 'studs' plugging yours if you don't see bolt heads on the other three ports.

The pix Tom posted show what look to be brass(?) caps installed on the OEM air injection ports' screw in-fittings. Others have installed long bolts like you originally tried.

Well.... Bad news....
I got a longer bolt and threaded it in enough to plug the hole until I could order a valve adjustment screw like listed above. The other 3 holes still had the plugs in there and tight.

I started the car and it ran great like it used to. After about 15 minutes on the road the car started to hesitate and as i was pulling over white smoke poured out the tailpipe and the car died and would not restart.

Had the car towed home. Anyone want to buy a new project car?

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The EGR and the Air Injection are 2 different systems. The holes shown are for the AIS, which uses a pump to force air into the exhaust ports, diluting the exhaust gasses. The EGR takes exhaust gasses and puts them into the intake, in this case the air cleaner (right above the throttle body).


The Cap'n

That sucks.

I was in no position to stop when I lost my 'plug' (night time in a really bad neighborhood), so I hobbled it home to find the problem the next day.

Even after I replaced the plug, it never ran right again. We ended up pulling the engine out and had a 2056 built up with new heads.

I still haven't taken the old heads apart to see what actually happened, but I think I drove it too far (about ten miles), sucked in a lot of cold air and it warped and exhaust valve


Take the top end off to see what happened ... hopefully you only need a valve job

No worries.

I'm serious about selling it though if you know anyone close to the East Bay Area.

Craigslist Ad:
http://sfbay.craigslist.org/eby/cto/3032554322.html

Update: Yesterday I charged the battery and she fired right up! I changed the engine oil, drained and refilled the transmission with some fresh 80/90 GL5 gear oil and cleaned the battery terminals. Everything seemed to be fine so I took it for a drive but stayed close to home.

After about 15 minutes of driving around it started to sputter and hesitate and died just like before. It would crank over but not fire and there was a strong smell of gas from the tailpipe. I pushed it back into the garage and let it sit overnight and this morning it started but after some cranking and sputtering.

I'm guessing that after heating up something is causing the spark plugs not to fire and then the engine floods and needs to sit for the gas to evaporate out. Maybe the coil?

Any thoughts or ideas before I start buying parts? Pretty sure I can get the coil tested locally but not sure if that will test OK in a cold state.

Thanks in advance.

Yes, coils can break down when they get hot. Been stranded on the highway more than once from dead coils, and not just in 914's. any coil. They work fine till they get hot, then quit. Not saying this is your malfunction, but it is a symptom.

1st ... I would ohm out the CHT ... pain in the ass to get to ... I say this because I bought a car with the CHT disconnected. I tried to start it and it wouldn't. Filled the exhaust with fuel. When I discovered the problem, I hooked it up and it fired off .. blew raw fuel out the exhaust pipe. When they go bad, it causes all sorts of problems.

2nd ... I would check the MPS. Had one go bad in Moab, UT. No start, shit piles of fuel in the exhaust. Had a spare, changed it and fired up and ran till I sold the car 2 years later.

3rd ... when it quits, check for spark. If none, look at the coil and condenser. When heated up, the coil can go bad.

That's the way I would proceed ........

Sounds like a failing CHT or MPS. Will your MPS hold a vacuum?

Thanks for the suggestions. I think I might rule out the coil because today when I started the car it fired right up but ran really rough. The idle is now really rough and when revving the engine even a little the car shakes. Its not longer drivable. I'll check the CHT and the MPS. Another suggestion was to see if the MPS holds a vacum. Is there an easy way to check that?

I use a Mighty-Vac

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Start checking all the FI components. If you have D-jet FI, a good place for trouble-shooting info is Paul Anders' site Click Here

Your symptons are very similar to mine when the CHT harness wire was broken and making intermittent connection.

Check the resistance on the CHT on the CHT lead, then check it through the FI wiring harness at the ECU connector. Wiggle the wires when testing and see if the resistance changes.

My lead was broken on the harness side just before the CHT connector.

Yesterday I took a look in the engine bay and found the vacuum hose had fallen off the MPS. I hooked it back up and the car strated right up, idled great and ran strong. I took her for a drive and she died on me again. This time when trying to start it just cranked and this time I had a puddle of fuel under the tailpipe. This is consistant with what you guys have said for a failing CHT and I have seen this described in other posts as related to the CHT.

I ohmed the CHT last night while the engine was still hot and got a reading of 132 at the CHT plug. The PO installed a 270 ohm resister in line with the CHT so i took it off and will test the CHT connection at the ECU plug tonight.

Does anyone know why the PO whould have added to 270 ohm resister to the CHT?

Also, after taking off the resister the car ran and no more gas in the exhaust but now it idles up and down and almost dies.

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That's a factory part for the 73 2.0 system.

Double-check that MPS hose....

--DD

Change out the CHT. They're not particularly expensive and if you are getting erratic running issues it's a cheap thing to try. I had a 912E (same engine) that ran great most of the time but would occasionally just stop. I checked the CHT multiple times and it looked fine, but after swapping it out, no more problems. And once I had the old CHT out I could easily confirm it was dead.

This sounds like exactly what's going on with yours.

The only problem I see with buying a new one is that you'll have some time finding a -017 CHT. The -012 is usually availible but it's not compatible with the '73 1.7/2.0 ECU.

I've got a '71 that the PO upgraded to a 2.0L (not sure of the year) and the post above
shows that I have a factory part from a '73 2.0L. Pelicanparts stocks the CHT but specifically excludes the '73 2.0L model. Any advice on this? What is the difference and am I out of luck getting a new CHT if I do indeed have a '73 2.0L in the car?

http://www.pelicanparts.com/cgi-bin/smart/...29%2C%20Each%20

The wrong new one is going to be 'righter' than the broken one.

Brad Anders (D-Jet guru) says on his tech page that there shouldn't be a significant difference.

Remember the CHT is only for warmup. Once the engine is hot is basically does nothing. So even a brand new 'wrong' CHT will be right at operating temp.

I might have some good news! I pulled the ECU and according to Brad Anders' page my ECU is from a '74. Part#: [0 280 000 044], [039 906 021]

Looks like i'm good to order a new CHT sensor from Pelican.

I did also notice that my distributor has a vacuum line on it that the Haynes manual shows should go back to the throttle body but my throttle body only has one stub for a vacuum hose and its already got the green vacuum line from the bottom of the distributor connected to it. Any ideas on if this is OK to leave as is? Or do i need to cap/T this in somewhere? See picture below the ECU picture below.

Thanks again for everyone's help with this. Its been a good learning experience so far!

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Check out the hose diagrams on Pelican ... one of them should be right for your system.

CLICK HERE

If there is no fitting on the throttle body for the advance line, leave the line disconnected. Just like it is now. Many 74+ 914s didn't have vacuum advance at all.

--DD

So I replaced the CHT and when I was removing the old one i found that it wasnt even hand tight. It must have loosened up over time but since I already had a new one, I replaced it.

After putting in the new CHT the car fired right up and idled really smooth but as soon as the engine started to heat up, the idle got really bad and the car would die. starting it and keeping my foot on the gas shook the car extremely bad so I put the 270ohm resister back inline with the new CHT and this seemed to fix that problem.

I took the car out for a nice long drive because the engine was idling great again and about 15 minutes later the car started to choke and it died again with a strong smell of fuel. So replacing the CHT didnt fix my problem.

After the car dies like this it just cranks and cranks. But the last time if i held the gas peddle down and cranked it for a good 30 seconds it fired up but would not stay running unless i kept on the gas and revved it above 2500RPM.

After the car cools down it seems to be OK again. Failing fuel pump? What should I check next?

My car did this exact same thing several years ago. It was finally sourced to an extremely frayed ground wire in the bottom of my distributor (only 2-3 strands were still making a connection). The car would fire right up and drive great when cold - then start running like crap and eventually die. once it cooled off, if would start right up again. I was sure it was fuel related. But once the wire was fixed, I never had the issue again. Its been 15 years.

Sorry for the out of left field idea.....

Check to see if you have compression. If you don't have compression on that one cylinder it will flood and then not fire which would result in the fuel your seeing. I had the same problem with my westfalia. With a dead cylinder it would always fire right up and then run poor once warm and then would not start after stalling. You should perform a leaqk down test. If you don't have the tools one quick and red neck method is to start the engine after it has cooled off and very quickly feel the exhaust right at the cylinder if it isn't even warm then that cylinder is pooched. You could have burnt your exhaust valve.

Regards'

Jon

There's a real easy method to find a dead cylinder ... pull the plug wire for a cylinder (one at a time) and if the RPM doesn't drop, you've found it.

Thats not nearly as fun as burning your fingers

True ...

I also had a similar problem to yours and was traced back to dodgy injector connections, which only manifested themselves when hot - when it's playing up wiggle the injector electrical connectors a little, one at a time.... It may just fire into life...

A bowlsby engine bay loom fixed my electrical problems for good..

I tried this today and the RPMs dropped when unplugging each spark plug wire from the plug individually.

I'll have to keep digging... Wish I had more time to troubleshoot this thing.

Thanks again to everyone for all the great help and direction! You guys are the best