New to the Forum - 73 1.7L FI, questions about running rough Options

[tadink]

Hey all - Please allow me to introduce myself and I'll post some pix as soon as I can. I'm a longtime PCA member and have restored a 67 911 that is still in the family....now I've gone an purchased a 73 914 1.7L Fuel Injected car in the Bay Area. It has been sitting for a bit, does not have appreciable rust, and seems in generally good shape apart from some mostly minor issues.

Question - after having been sitting for 6+ months, she fired up and ran - but a bit rough. No engine noise or knocks, but the idle is rough, it stalls at low rpms, and is pretty rough except under a good amount of throttle. I'm thinking dirty injectors at least - what is the best course of action from here?

options - add injector cleaner, good gas, run the bee-jesus out of her
option2 - get the thing to the mechanic and let him sort it out
option3 - ????

your help and guidance is appreciated - I've had great success with the lads on the Pelican Parts 911 board, and you all seem quite helpful as well as I've read thru the posts on this board. Hope to be able to contribute as well as learn...

best

tom

[underthetire]

Do a full tune up. New wires, fuel lines, valve adjust. That way you at least have a starting point.

[rick 918-S]

Vaccum leaks from old hoses, bad gas and sticking injectors like you said. Full tune up like was suggested. Drain the tank, I think Jake posted something about bad gas causing valve sticking or something like that...Can't remember exactly but I recall it was very bad.

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[kerensky]

Vacuum leaks from old hoses

This. Fuel injection systems, especially any made before the mid 90's or so, are very sensitive to vacuum leaks, and your D-Jet is no exception. The later L-Jet cars were so bad that a leaky gasket on the oil filler cap can make 'em run like poo.

[simonr]

Fresh gas can always work wonders on a car thats been sitting. Also replace the fuel filter.

[eric9144]

Do a full tune up. New wires, fuel lines, valve adjust. That way you at least have a starting point.

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[tadink]

Do a full tune up. New wires, fuel lines, valve adjust. That way you at least have a starting point.

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Hey all - many thanks for the help - I'll go see about sorting out the vacuum lines and see if there is one that is the culprit - I'm guessing that the vacuum malfunctioning would also lead to the smell of the exhaust giving that fuel mixture too rich odor? And it explains why the hard acceleration might be fine but the mid throttle is really choppy.....It certainly gives me a place to start.

Absolutely will replace the fuel filter, and will do a complete tune-up and valve adjust to get a baseline....all great suggestions and good advice.

Injector cleaner - waste of money or worth a try?

thanks all! tom

[ezbngreen914]

I got the same car (1973 914 1.7) back in Nov. 2010. I'm no expert, but when I started using Ethonal free gas and lucus top end lube/injector cleaner and drove it hard it seemed to be much "happier". after a couple of weeks of hard driving (and maybe for the whole time I've owned it for that matter) I noticed 2 substantial gas leaks (one from an injector and one from the fuel rail/injector hose connection). Probably goes without saying but something to look out for. What color is yours? When was it Born? Lets see some Photos (IMG:style_emoticons/default/beerchug.gif) (IMG:style_emoticons/default/welcome.png) This really is an invaluable site for keeping these cars on the road.

[underthetire]

Fuel injector cleaner: old berrymans in the tank along with a can of marvel mystery oil worked for me. can't hurt.

[tadink]

Fuel injector cleaner: old berrymans in the tank along with a can of marvel mystery oil worked for me. can't hurt.

Hey y'all - loaded her up with injector cleaner and high test gas - drove from Alameda to Napa tonight in traffic, not that fun, but the car ran pretty well when either ON the gas or OFF the gas.....but not that great in between. Still a lot of bucking on mid-throttle or light-throttle - I need break this philly!

runs much better in a higher gear with more throttle, not so good at high rpms with lighter throttle, lots of missing / bucking. Going to change the plugs over the weekend, found a vacuum tube that was not plugged in, and the rest look pretty sketchy!

Pix coming soon....

td

[swl]

There are good mail order fuel injector services available. Costs about $15/injector if I remember right. They strip them down, clean, but in new screen, seals, test and certify. Probably a good investment. Yellow top injectors are getting NLA.

Check your MPS to see if it is holding a vacuum. Also the vacuum advance on the distributor.

Brad Anders site is probably the best source of information on D-Jet.
http://members.rennlist.com/pbanders/djetparts.htm

[scott_in_nh]

Check that both the distributor vacuum advance/retard and MPS are holding vacuum.
Remove and clean the FI points - when these are dirty it acts like clogged injectors.
Take the cover off the TPS and clean the board carefully with a pencil eraser.

[perrysan]

When the engine is cold, does it idle/run OK, but then get worse once things are warmed up? If so it could it be the engine is running too rich because it's not getting the message that the engine has warmed up.

[tadink]

LOL - - you guys are the best, and I'd take your advice if I knew what the heck you were talking about - - - MPS, TPS, huh?

I need an idiot's guide to fuel injection, clearly! Is there such a resource anywhere on the site? something that takes total newbies like me thru the basics of what the heck I'm dealing with?

Pix in the morning - got the driver's window replaced (broken out by hoodlums) and put on the inner door skins, inside door handles, and started taking some inventory of what this 'near barn find' has to offer. The vandals took most of the screws out of anything that had a screw in it - - - what is the value of a screw???? - - - - and so there is a bunch of stuff rattling around loose! They also cut out the headlamp motors, so I have that to deal with yet. AND they took all the fuses! really, the fuses???? good grief....LOL

but, all in all, minimal rust that I could find. Tomorrow I dig into the engine bay - and I'll look around for an MPS or a TPS -

thanks for all your help - - -

td

[tadink]

Check that both the distributor vacuum advance/retard and MPS are holding vacuum.
Remove and clean the FI points - when these are dirty it acts like clogged injectors.
Take the cover off the TPS and clean the board carefully with a pencil eraser.

Hi guys - a couple of suggestions to check and see if the MPS is holding a vacuum - uh, HOW does one check to see if a vacuum is present / holding?

thx in advance -
td

[swl]

I need an idiot's guide to fuel injection, clearly! Is there such a resource anywhere on the site? something that takes total newbies like me thru the basics of what the heck I'm dealing with?

That would be Brad's site. It looks a bit overwhelming but if you take an hour and go through it at you'll have a good grasp of the parts involved and understand the secret language (IMG:style_emoticons/default/smile.gif) http://members.rennlist.com/pbanders/djetparts.htm

The MPS is the manifold pressure sensor. often described as looking like a hand grenade. to the rear of the battery mounted to the inner fender well. It controls the enrichment process when you open up the throttle. The correct answer to the question of holding a vacuum is to buy or rent a vacuum puller (small pump with a guage on it). Bring the vacuum up to the specided test value (see Brad's site). And watch to see if it holds that vacuum. The quick and dirty first check is to just suck on the port and use your tongue to seal off the port. You will look real silly but if the diaphram is leaking badly you should know right away. If it seems to hold you should probably do it again with the vacuum puller to ensure there aren't slow leaks.

[tadink]

I need an idiot's guide to fuel injection, clearly! Is there such a resource anywhere on the site? something that takes total newbies like me thru the basics of what the heck I'm dealing with?

That would be Brad's site. It looks a bit overwhelming but if you take an hour and go through it at you'll have a good grasp of the parts involved and understand the secret language (IMG:style_emoticons/default/smile.gif) http://members.rennlist.com/pbanders/djetparts.htm

The MPS is the manifold pressure sensor. often described as looking like a hand grenade. to the rear of the battery mounted to the inner fender well. It controls the enrichment process when you open up the throttle. The correct answer to the question of holding a vacuum is to buy or rent a vacuum puller (small pump with a guage on it). Bring the vacuum up to the specided test value (see Brad's site). And watch to see if it holds that vacuum. The quick and dirty first check is to just suck on the port and use your tongue to seal off the port. You will look real silly but if the diaphram is leaking badly you should know right away. If it seems to hold you should probably do it again with the vacuum puller to ensure there aren't slow leaks.

Thanks for the link - I spent a couple of hours there and chasing all the links from that site so I think I know that I don't know very much now, but might have a chance at spotting possible errors....

Re: your suggestion about checking the vacuum - FANTASTIC - that's the sort of help I need. Take off a really dirty hose and suck on it, holding the vacuum with your tongue! LOL That should pretty much convince my wife that I have indeed lost my mind - if the purchase of this thing did not already!

I'll take you at face value (and assume you are not just initiating a newbie to the board with a silly task!) and go see if I can find the MPS thing and see what might be attached to it - - - I did manage to find two hoses with bolts stuck in them. I'm thinking this might not be 'factory original' since the bolts are oversized and rusty. Doing the diagnosis now to see what custom feature this might be - and to ID the hoses.

seriously, thanks for your help on this!

td

[SirAndy]

I think it's time you post some pics of your engine bay. It'll help to be able to point at things that look funky. And yes, a quick test of the MPS can be done by sucking on it to see if it holds vacuum ...

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[tadink]

HI guys -

some pix - 1st is from the port side looking in
2nd is starboard side looking at the 'spare hoses with bolt plugs' in them
3rd is the 'pride and joy'

History is that this is a bit of a barn find - it was in storage and the guys at the yard decided to help themselves to as many bits as they could unscrew - so there are things not there that I might not notice since I'm not that familiar with the teener. Some things I do know are missing are the headlamp motors (cut the wires to get them out), and various trim bits.

She's had a bit of a shunt to nose and the hood is bent in the middle a bit - so I'll replace that, the front bumper, and the front struts asap.

still, it starts, runs, makes good noise. with a bit of work, should be just fine.

along with the purchase (very low price + a case of wine) came some never installed coilover bilsteins for the rear.

I'll post an inventory of the 'wish list' for parts at the end of the day - -

thanks again!

td
Napa / SF Bay Area

so, all in all, if I can get her on the road without too much issue, I think it will be a fun driver.

[swl]

There are a few things that are just out of site that might explain a lot

Can you take another picture that would show that which is immediately below the frame of the current picture #2. That is where the MPS and the decel valve are. Just outboard of the intake runners.