Idling Rough, After a good drive on the highway???? Options

[martinef1963]

Here is the problem with my 72, 914: It starts in the morning - no problems, drives during the first 30 minutes like a stallion, and has plenty of pep on the highway(1.9L -Big Bore Kit), however, once I get off the highway (slower RPM) - I can't hold an idle. Engine starts to vibrate like if it's missing an injector or two.... I pull and reset, but still the same problem.....

The next morning it runs wonderfully again! I got to work this morning, stopped the car and it was idling just right.... (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) This is my daily driver.....

I'm tempted to buy a new FI harness from Bowsley (spelling), but would like other avenues if anyone has any - less expensive advise.....

I'm educating myself on the FI system - it's a bit overwhelming, but I know I will get there, in the mean time - any suggestions?

Thanks - the Newbie

[mightyohm]

It's probably running too lean once it warms up. What modifications were done to the FI system when the displacement was increased? I assume it is d-jet and the engine was a 1.7 originally? My 1.7 runs inconsistently too, but if I bump up the idle speed to 1100-1200 rpm it's less noticable. That is how I have lived with it for 2 years now.

[martinef1963]

No modificatons were done to it, not that I am aware of. Currently I've matched the numbers for the ECU, MPS, and Pressure regulator. I'm thinking of the FI harness.

It sometimes idles at 1200 to 1500 RPMs, but not consistent enough for me to think that someone bumped up the idle. I donno.

When it warms up, what is causing it to run lean? what is the angle?

thanks - the newbie.

[mightyohm]

QUOTE (martinef1963 @ Jan 4 2005, 01:44 PM)

No modificatons were done to it, not that I am aware of. Currently I've matched the numbers for the ECU, MPS, and Pressure regulator. I'm thinking of the FI harness. It sometimes idles at 1200 to 1500 RPMs, but not consistent enough for me to think that someone bumped up the idle. I donno. When it warms up, what is causing it to run lean? what is the angle? thanks - the newbie.

Normally the fuel injection setup is matched to the engine. Ie. a 1.7L injection system will only work well with a 1.7L engine. You have a mismatched setup since you have a 1.9L engine with what I am guessing is a 1.7L d-jet setup. Some of the other guys on here know more about this than I do, but I am guessing you will need to modify your MPS to get it to run right assuming everything else checks out ok.

[jr91472]

maybe apples and oranges, but here goes...

my 72 1.7L is carbed and I have experienced the same issue. I have reset the idle at ~1200 (after warm up, but before "highway drive").

I never liked the feel of the idle at 900 anyway....seemed very rough.

[jwalters]

Maybe yalls tachy-meters are worn out and just not showing the correct engine speed so you can set it up right in the first place---

Go buy a real tachometer and wire it up quick like in the engine bay and start the car--see ifn this is just one or the only problem thats screwing everything up--

PS-I have seen in the past the tach get so messed up that it interfers with the spark output from the coil where it is attached to----



just my $0.02

[DJsRepS]

http://members.rennlist.com/pbanders/DJetParts.htm Copy / Paste this to your browser. You can match all you FI parts by the #..... The FI harness can be rebuilt at home with parts a good eletronics parts store NOT RaidoShack. Ive herd it never hurts to start with the basic's before blameing the FI system valve adj, compression check, test find and fix vacuume leaks inc the MPS and Vac adv diaphgram, if it has been awihile pop the dist and clean and lube and ohm out the FI points and lube lobes, clean and lube advance plate, clean lube and ohm/set TPS switch, check FI harness grounds , check FI ECU connection (a feeler gauge in the terminal can spot loose conections), check fuel filter, check fuel pressure 29-32, pull injectors two at a time leaving on the gas lines and wiring and place a small juice glass under each, pull all primary wires off coil neg and mainly the pos, then crank over 30 to 40 sec to see spray pattern and later compair volume look for cracks and leaking after cranking. If all that dosnt help let me know and I will dish out some more.....Here is a pic of my home built harness, the boots are from large alagator test leads. Yellow gas lines colored heat shrink, gas port/freon valve, main harness spiral wrap, every terminal wire clamp opened and copper conection checked and spade pinched a little if needed.

[TheCabinetmaker]

Looks like you still got those stupid hose clamps on the FI. (IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif)

[DJsRepS]

I forgot to mention because I removed mine but check the aux air regulator and PVC valve as well. A bad seal leak eg sucked valve cover gasket or Oil cap left off dipstick even has a seal in the metal cup that can cause our cars not to run as should. When you do a compression check take note of the plug burn 2 good 2 bad means check the trigger points.

[martinef1963]

Thanks guys for the sound advise - from the read of it - I have my work cut out. I didn't mention that I have electronic ignition and don't feel that to be a weak spot. Otherwise I will copy, paste, disect, and get to working - much thanks.

A Newbie. (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)

[mightyohm]

It makes sense to check all the basics. Plugs, wires, timing etc. Fuel pressure, grounds etc.

Did it ever run right? Is this a new problem or has it always been this way?

I still think you are probably having problems because of the non stock displacement. If the cam isn't stock either you will have even more issues.