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Posted by: Tab914 Aug 15 2004, 06:54 PM

Hey guys! Hope someone out there can help me out. I'm having problems with my engine coughing ( missing ) and sputtering when accelerating and also on steady revs at about between 2000 and 3000 rpms. This causes the car to lose power and shutter. The problem is worst once car is warmed up. The car starts great without even having to step on the gas but idle sometimes becomes erratic. I adjusted the dwell, timming ( with strobe ) and idle ( idle as best i could ) but can't put my finger on the problem. I would appreciate any tips, info, or idea anyone might have. Cheers, Dominic.

p.s. I'm in the Canadian rockies, would elevation change specks car should be at??

Posted by: bondo Aug 15 2004, 07:00 PM

Engine missing? Where'd you see it last?

(sorry, couldn't help it)

Posted by: Tab914 Aug 15 2004, 07:08 PM

Hey Royce! I was expecting that one.

Posted by: bondo Aug 15 2004, 07:22 PM

On a more serious note.. if it still has the original d-jet, maybe it's the cylinder head temp sensor? I think the Manifold pressure sensor is supposed to adjust for elevation changes.

Posted by: Tab914 Aug 15 2004, 07:26 PM

How would I test that sensor??

Posted by: bondo Aug 15 2004, 07:30 PM

Everything you could possibly need is right here: http://members.rennlist.com/pbanders/djetparts.htm

If I remember right, the sensor should be 2.5k or so ohms when cold, and under 100 ohms hot.

Posted by: Tab914 Aug 15 2004, 07:31 PM

Will check that page out right now and go from there. Thanks Royce.

Posted by: nebreitling Aug 15 2004, 07:41 PM

mps automatically adjusts for elevation -- Jeff Bowlsby just taught me that yesterday...

check out the CHT and ALL of your electrical/ground connections.

check TPS.

i'd suspect ignition, as well.

Posted by: Tab914 Aug 15 2004, 08:25 PM

Hey Nathan! This might sound stupid but what is the CHT? Also can you tell me how the ignition might have something to do with this? Thanks Nathan.

Posted by: SLITS Aug 15 2004, 09:49 PM

I ain't Nathan, but if your high tension wires (in Canada, they are known as spark plug wires) are old, they can arc to ground or between each other. I used to wait until it go dark, fire the engine and rev it a couple of times to see if they were arcing. There is a better method with a VOM (volt-ohm meter).

In the cap, the spark can arc to ground. This is easily seen inside the cap as black fine lines that look somewhat like lightening bolts. Or the contacts can be so worn/corroded that the spark doesn't jump from the rotor.

Bad spark plugs

etc etc etc on ignition.

Other than that -

Bad tracks in the TPS (throttle position sensor)

Dying fuel pump - can't get up to operating pressure when warm

CHT = cylinder head temperature sensor - near #4 cylinder in a hole thru the tin - a bitch to get at. Otherwise
known as temp sensor #2

Posted by: Tab914 Aug 15 2004, 10:43 PM

Thanks Slits! The fuel pump is brand new, I checked the temp. sensor and it is showing the ohms reading. The plugs are good. I have the throttle position sensor in my hands right now. Took it off to check the contacts. Found some corosion and cleaned all of that off. What exactly do you mean by " bad tracks" ? Also is it possible to test the switch with a meter while it is out of the car? If so how? I will have another look at the plug wires and inside the cap. Might also use the fireworks method in the dark just for the hell of it.

Posted by: McMark Aug 15 2004, 10:46 PM

Sounds like a TPS problem to me. Bad news, you can't test them reliably. [edited to remove moronic statement]

Posted by: SLITS Aug 15 2004, 10:49 PM

The site on D-Jet will talk about the tracks in the TPS = over repeated cycles, they will wear, just like ignition points.

Posted by: Tab914 Aug 15 2004, 10:52 PM

I have to say it's got some good grooves on there. You guys just might be right. Anyone know where I can get one cheap??

Posted by: nebreitling Aug 15 2004, 10:53 PM

you talkn about the fi points, mark?

Posted by: nebreitling Aug 15 2004, 11:00 PM

tab914, is this a new car that your bringing back to life? or did this problem recently develop?

in the case of the former, it may be difficult to track everything down that's wrong. if the car has sat for a while, then you could have a compound problem. be methodical, it will save you time and money in the long run.

anyway, if your tps is scored badly, you'll want a new one anyway. google the part number for the lowest price.

but before you dig into the FI, i'd make sure that your points, rotor, cap, wires etc. are good. check the timing if the car will run. then move on. fuel pressure, etc.

things like MPS and FI trigger points are harder to test for -- i save those for last.

Posted by: McMark Aug 15 2004, 11:03 PM

Sorry I'm a moron. I think the TPS is bad. (edited previous post). Still no definitive way to test a TPS.

Posted by: Tab914 Aug 15 2004, 11:11 PM

Hey Nathan! This is a car I picked up last summer and have been working on since. This problem is new though. The car ran fine. Finally got the car certified and plated and now this. Will deal with this switch and move on to rechecking everything. I did unplug the switch to see if the problem would go away but it persisted even when the switch was unplugged. I read somewhere that if the switch was the problem, the coughing would not occur when switch was unplugged. Do you know if that is accurate?? Does this spawn any other ideas for anyone?

Posted by: nebreitling Aug 15 2004, 11:28 PM

unplugging my TPS made my car run really rough, but i assume that any specific throttle enrichment issues would cease.

if the problem still manifests itself, i'd look elsewhere -- like the FI trigger points. does your gas mileage suck? running real rich? bogged down? -- or just a "flat spot"?

Posted by: Tab914 Aug 15 2004, 11:35 PM

Yeah gas milleage does seem high and car sometimes smells like it is runnig a little rich. When car is warmed up it really sputters and buck on acceleration. ( or lack of acceleration )

Posted by: Tab914 Aug 15 2004, 11:36 PM

Forgot to mention also get an occasional puff of smoke on ignition.

Posted by: nebreitling Aug 15 2004, 11:54 PM

i'd go ahead and pull the dizzy and replace the trigger points. it'll cost you about 120 buck, iirc. take the dizzy apart and clean it while you're at it.

meanwhile, does your mps hold a vacuum?

Posted by: Tab914 Aug 16 2004, 12:21 AM

The pressure sensor seems fine. What is a good way of testing it? By dizzy you mean.......

Posted by: nebreitling Aug 16 2004, 11:25 AM

distributor.

set the car to TDC. pull dizzy, noting it's orientation. plug up the hole with a rag or something. don't move engine or car while dizzy is out. take apart, clean, replace FI trigger points. replace dizzy the way you found it. set timing and dwell again.

might do the trick (might not )

re. MPS, borrow/steal/buy a vacuum pressure pump. pump up some pressure, see if it leaks down... hope it doesn't ($$$$)

Posted by: Jacco Aug 16 2004, 12:21 PM

hey there,

I have the very same problem with my 2.0 djet. at around 2700 rpms it bucks at steady speeds. Drove to France and back (1900 miles) kept the revs above 3000 and no problems that way.
still haven't figured out what causes this.
my tps sensor tracks are worn, might also be dirt in there making a short and fooling the ECU...
about a year ago I checked all the electrical (and vacuum) connections and problems seemed to be less only shortly though
will be back at it this winter, new vacuum hoses and some other stuff, maybe a new wiring harnass (working on it right now)

If heard of more 2,0's with djet having this problem, it seems to be quite common...

hope there's a fix for this..... (apart from a 3.0 six )

interesting to read about this!

greets
Jacco de Haan
Delft, the Netherlands

Posted by: nebreitling Aug 16 2004, 03:56 PM

sounds like TPS fo' sure

Posted by: mike_the_man Aug 16 2004, 04:13 PM

Tab914,

Canadian Tire has vacuum gauges in their Loan a Tool program. Pull a vacuum and see if your MPS leaks. If so, that will cause your car to run rich. It could be the problem. Give it a test and let us know. Good to see another Teener in Canada. I drove through Banff last month. If I had of known there was a fellow 914er there, I would have stopped by and said hi. I usually get out that way once or twice to ski in the winter, too.

Good luck,

Posted by: Tab914 Aug 16 2004, 05:41 PM

Well it looks like the problem has been resolved. Here is what was done; new distributor cap, replaced a plug wire that looked suspicious, took off and opened the TPS and cleaned all it's contacts, moved it's brushes so that they sweep on new lines and reinstalled as per specs. Rechecked timming, dwell and idle. Here is what I think is the clincher; I discovered a resistor between the head temp. sensor that didn't seem to belong and didn't show up on the electrical diagrams. After test on both sides of the resistor discovered that it was sending erronous signals to the ECU. Removed it and and reconnected sensor wire directly to the harness connector. Took the car out for a test drive and no sign of the problem. Took car up to temperature where it would buck before and still no symptoms. So, looks like the problem is solved but am keeping my fingers crossed that this is not only temporary. I want to thank you guys, especially Nathan and also Slits and Royce. Hey Mike, next time you are in Banff skiing look me up. I am the daylodge manager at Banff Mount Norquay, one of the ski resorts here. I'll hook you up with some free ski passes and a few beers while we exchange 914 stories over lunch or apres ski. We should exchange emails so you can contact me before coming up. Again guys, thanks alot for all your input and help. If you have photos of your cars I would like to see them if you can post them. Here is one of mine. Cheers, Dominic.


Attached image(s)

Posted by: mike_the_man Aug 16 2004, 09:07 PM

Dominic,

Free passes would be awesome! I would owe you a few beer for that. If you're ever out this way, look me up. I'll slide you an email sometime soon!

Posted by: bondo Aug 16 2004, 09:16 PM

What year is your car? I forget which, but one year 2.0 is supposed to have a resistor on the CHT.

And you're welcome!

Posted by: mike_the_man Aug 16 2004, 09:22 PM

73 should have the ballast resistor, I believe.

Posted by: Tab914 Aug 16 2004, 09:29 PM

This one is a 74 2.0lt. Also have a white one back in Ontario which is a 73 2.0lt. Will be there in a bit and will have a look.

Posted by: Tab914 Aug 16 2004, 09:31 PM

Any time Mike. Do you know Norquay. It's the one that is actually right in Banff. Just before Sunshine. Make sure you send me that email and we'll hook up.

Posted by: bondo Aug 16 2004, 09:37 PM

Someday my wife and I plan to visit Banff. It looks like an absolutely beautiful place. What's the best time of year to go if you don't plan to ski?

Posted by: Tab914 Aug 16 2004, 09:55 PM

Well, if you like fishing, hiking, golfing or even just sightseeing in nice hot sunny dry ( very low humidity ) weather, from June to mid September is great but the town is very busy with high tourist season. Otherwise you can do all those things in a bit cooler weather in the Spring or Fall when the traffic is a little lighter. The shops aren't as busy and the tourists attractions aren't as crowded. But in all honesty, it's quite breath taking here pretty much all the time. Moved here from the east ( Ontario ) 8 years ago with plans of spending one year in the rockies. Now I can't tear myself away. If you ever do come around let me know. I'll show you the good bars in town.