Technical Need Help - Slow Idle

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Technical Need Help - Slow Idle

beng

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Wondering if anyone out there has had this problem. I have a 1979 X1/9 with a 1500. The engine runs strong except when it is warm (choke off), the car tends to idle very slow. If you raise the idle by the carb adjustment, it revs too high when cold. I checked the timing and it seems OK. I also checked the valve clearance and it is good as well. I thought that the valves were involved since the car seems sort of delayed with respect to the gas pedal response. The last symptom that I believe is related is that the car has a knocking sound when under acceleration. This knock must be from the intake or exhaust as it is not on the exterior of the engine. I have a spare 1300 engine and thought that I will swap the heads to see what happens but I would really like to know what the problem is before I start messing with this.

Any ideas would be much appreciated.

Thanks
 
when you say knock,does it sound as though the engine is "pinking" ? it sounds very tinny.or does it sound more pronounced and louder?pinking is too much ignition advance or a choked up head.the noise could also be abroken valve spring.the louder noise would be bottom end problems.have you recently touched any settings?
i think you need to set the carb up properly as well.hard to diagnose without seeing it.dont suppose you live in manchester do you?
 
Are you running the automatic choke on your carb?

If so there are three adjustments that affect the idle speed on the European models however I suspect you're on the other side of the pond and may have all the EGR system to compete with too!

No.1 is the screw that acts onto the throttle shaft on the back of the carb. (rear luggage compartment end)

No.2 is the screw on the automatic choke mechanism and is on the right of the carb on a long lever (you adjust it where it says weber on the float bowl).

No.3 is by rotating the automatic choke coolant housing (the bit that says weber with two coolant hoses coming out of it.

If your engine is idling okay when hot now, then the first adjustment I would make would be to rotate the coolant body to drop down the revs when cold.

The knocking under acceleration is likely to be pinking as already suggested. As your timing is correct (you have checked full advance by revving the engine haven't you?), I would check the main jets for any slight blockages that will cause the engine to run weak under hard load. Take the air cleaner off and you'll see four brass screws looking up at you from the centre of the carb. Remove the two larger ones and the main jets are at the bottom. Give these a good clean out along with the emulsion takes (middle bit) and the air correction jets at the top to see if this helps you. Petrol and a tooth brush will do the job, getting the bristles into all the holes.
 
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Thanks so much for the ideas. First, I would like to comment on the knocking sound. Although I'm not sure what "pinking" sounds like, I starting to think that it may very well be the bottom end. Could it be that I have a piston knocking on a valve and perhaps this is causing my other symptom problems? Would this cause idle type issues? You see, I have messed with the settings (and have tried everything) that I would really need to start from the beginning again.

As far as the choke, this car has an automatic version and all the EGR stuff. (I also have a '74 and preffer the manual choke and no polution control systems!) I didn't know about the rotating choke housing. This could be a fix. I will clean the jets as suggested and reset everything to see if this helps.

On another note, I am located in Southwestern Ontario, Canada. Around here, there are very few folks that would touch these cars and if they do, they are too expensive or experimenting...Not much of a network. I appreciate this kind of feedback!

I will be working on this over the next week and will update on my progress. In the interim, if anyone can think of any other ideas, please let me know. (I'm starting to think I may have a few seperate issues.)

Thanks
 
The pinking is a bit like a clicking noise. You would only notice this when working the engine hard (thrashing it in fourth gear or labouring it up a steep hill in fifth)

I know the oil pressure gauge is notoriously un reliable....but.....have you noticed any drop in oil pressure at idle. The reason I ask is that if your bottom end is on the way out, you'll see a reduction in oil pressure. In fact thinking about it, does the oil warnng light come on at idle when hot as this will be more accurate than the gauge (my gauge reads zero at idle when hot and I know it has good pressure!).

The fact that your car is strong when cold would eliminate any issues with the valve gear. It would be knocking all the time if this was the problem.

On your idle mixture adjustment screw (the one in the recess at the base of the carb as you look from the passenger side of a LHD car) take it out, clean it up and then screw it about 1 1/2 turns out from fully home as a good starting point.

Another thought - do you have a vacuum advance on your distributor? If so take the pipe off the manifold (or where ever it goes on your emission control gubbins) and see if the diaphragm in the carb is sealed by trying to blow into it. Also, if it is okay, make sure that you disconnected this when setting the timing (If you did it with the engine running).

Good luck with you adjustments!
 
Now that you describe the "pinking", I know what you mean. Indeed, that is the sound and I believe this is it. You are also correct on the oil pressure gauge as I experiance the same low reading at idele. The warning light is never an issue and I do trust that I do have good pressure.

Thanks for the advise on the advance as I have not disconnected this in the past during the setting process.

Again, thanks for the good advice.
 
I've just realised that I made a mistake on the last post. When checking the diaphragm it is of course on the distributor and not the carb but I'm sure you already realised that!!

Regarding disconnecting the vacuum advance pipe, you'll find a lot of manuals don't mention this as it shouldn't effect the timing at idle or max rpm however as you're trying the set the base limit of the centrifugal advance is it always worth while removing any external factors that could affect the accuracy of the timing. We don't have vacuum advance on European X1/9's.

Do you need to keep the EGR and air gulp system (I think you have air gulp on yours) plumbed onto your car are are you legally ok to remove it. I've never had a great deal to do with these systems but I could imaging these could cause all sorts of running problems if not operating properly.
 
The polution control system can be removed as vehicles in Ontario only need to be checked and certified upto 15 years of age. After 15 years, they are exempt from emissions testing requirements therefore nobody would ever know! I did this on my 1974 model when I replaced the engine with a 1500cc but I used a carburator that did not have all the ports for the emissions system. I was lucky to find this carburator and don't think another would be available. I guess I'm not sure what to do with all the holes in the carburator once this is removed.

Do you think this is contributing to the overall running problems?
 
you need to reset the timing due to it being to far advanced.i would also remove the dizzy after setting it at no 1 plug and check for wear.same with the carb,it proberly needs a repair kit on it.best thing is a manifold and carb off an european car.perhaps buying one through the owners club.with the dizzy,you will have to check you are getting full advance.this will contribute to low power if not advancing enough.but i know you have carb and dizzy settings out.fix the settings before you do anything i have suggested.
 
Sumplug - we can't be sure that the ignition timing is out? Even if it was set with the vacuum connected this would not cause over advanced timing - it would do the absolute opposite. Ignition is set on No. 4 on an X1/9 which is something that catches many people out when refitting the distributor

Regarding a carb and manifold, I have these going spare here as they came with an engine I just bought for tuning. The carb will need a very good clean though but you can have them for the cost of postage. I've done away with the standard carb and am running twin 40's now. I'm fairly sure I have a spare distributor too (just the base) but these run off points so you may want to stay with your far more advanced electronically controlled unit.
 

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I've just been doing a little research on the air gulp system and this indeed can cause the engine to run weak although it would suggest this is more noticable when cold. If the valve is not operating correctly you may get a backfire on deceleration too.

For me I would just scrap off the full EGR and air gulp system. If you're running a catalyst, dump that too. All of these are sapping power out of an engine that even in European spec does not have enough power to do the handling justice.

There are a couple of good forums over there for people with X1/9's. Check out www.mirafiori.com and also xweb on http://www.network54.com/Forum/12159
 
RS.
sounds to me as though he is getting pre-ignition.that is too much advance.i think he has messed up his settings and needs to start from scratch.the dizzy i suspect is worn.so too is his carb and emission crap.i agree that the emission stuff should be junked.the timing and fueling need sorting though.
 
Wow...I really need to get to work here to let you know what I find. Unfortunately, I will not be able to do anything until the end of the week as I just can't spare the time at the moment.

Sumplug - What is a "dizzy" (this is not a term used on this side of the pond).

RS Pilot - I spoke to a fiat - Lancia parts dealer in Atlanta, Georgia today who basically indicated that the polution control system is generally a problem and tends to confuse the real issues. Although they can't recommend to remove, they can for racing uses. The issue is that my carburator is set up with all the ports to feed the system. The dealer recommended that it would not be a good idea to plug up the ports but rather to replace the carb with an older version, european carb, or the conversion carb they sell. The carb you are suggesting...is equiped with no ports for the polution control system?

I will start by resetting the timing and carb. Once this is complete, I will have a better idea of what is going on. I will report back the findings and hopefully be in a better position to establish the next steps.

Thanks again.
 
hi beng.
dizzy is short for distributor.start with the basics of timing first,then carb setting.then see what else if anything is wrong.the advance needs retarding[moving with rotation of dizzy,that is if dizzy rotates clockwise,the dizzy needs to go clockwise to retard and the other way to advance].good luck.
 
My carb has none of the emission control ports on it - just fuel in, fuel out and then water in and out for the automatic choke.

I've just finished repairing my other halfs 911 which was leaking like a sieve so I'll have enough time to clean up the carb internals and make sure it's servicable during the weekend.
 
Well I did some work on the car and started with the timing. I believe I had the timing pretty close except I could not get the car to idle under 1000 rpm long enough to get it set. I stopped at the point that I think is close. I set the timing this time with the vacumm advance disconnected...big difference. The first question I have is to RS Pilot who mentioned that cylinder 4 should be used versus 1. The Haynes manual indicates cylinder 1 so it is what I used. Am I correct or should I have used #4?

Now that I have the car running close to where it was before I started messing with it, I started to get the carburator set. I am currently at about 5 turns on the mixture screw and simply can not get the car to idle below 1500 rpm. Anything less than 1500 allows the car to die. This is the problem I have been fighting the entire time.

I have checked the vacuum advance, cam timing, valve clearance, and ignition timing and beleive Everything seems OK. I have to believe that the problem is related to the carburator. What do you think?

I am going to continue to work on this and will report accordingly. If you think of another potential problem related to the car not allowing the engine to idle, please let me know as soon as possible.

Thanks
 
Good to hear you're getting on with it.

When checking the ignition timing with the engine running you can use either No.1 or 4 as the distributor is running at half engine speed. When you have the engine timing set against the crank and cam marks you'll find that you are TDC with both valves closed on No. 4. If you check cylinder No.1, you'll find both valves are open. This is why you would replace the distributor whilst it is set to No.4 when using the engine timing marks.

If you cannot get the engine to run below 1000 at the moment, I would set the ignition statically using an ohmmeter or battery and test light. The fact that the vacuum advance is making a big difference is suggesting that the engine is running too fast for dynamic timing to be accurate. Set statically before moving any further.

For the engine not wanting to idle properly below 1500 would lead me to agree that there is a problem with the mixture although this is not necessarily the carb. That fact that the idle mixture screw is 5 turns out is suggesting a major air leak somewhere. Check for any free play in the butterfly valves, loose inlet manifold, bits of gasket missing......anything that coud let air in from the bottom of the carb onwards

I still have a niggling feeling about all your emissions plumbing. The EGR and Air gulp systems could cause problems with the mixture, specially if they have any cracked pipes etc. There must be a way of removing this, even with the stock carb set up.
 
Thanks for the advice RS Pilot. I will proceed with the static timing and I assume the it should be set to 5 degrees TBC in static mode just as I would target for dynamic setting.

I will also check for an air leak as this suggestion seems very plausible. I also believe that the emissions system is a source of concern. I was told by a Fiat parts source in the US that simply plugging the ports would actually make more of a problem as the carb was designed to run this way. I don't assume you have any experiance with this type of thing. You see, my other X1/9 has a carburator that was mistakenly shipped to the US in the 80's (there were Fiat dealers here then) and is believed to be from a Ritmo. This carb has no emissions ports on it and I removed the system from the engine...she purrs like a kitten!

Well, for now I will proceed with the suggestions you made above and see what happens. Do you think that the valves may have something to do with this? I need to get a hold of a compression tester just to satisfy myself that they are OK but do you think these symptoms may be related to a valve problem some how?

I will report my findings.
 
I just set my static timing at 5 BTDC too and find that it's spot on when running dynamically after.

Regarding your valves, the only issue I would even consider is a burnt out exhaust valve. You would hear a type of chuffing noise if this was the case as the expanding gases would be escaping before the valve opens. I've had a car with a burnt out valve and to be quite honest it made little noticable difference to how the engine was running. This was a Ford 1400 cvh though :yuck:

Set the timing and then try and find any air leaks on the intake system
 
Well, you were correct...There was an air leak. I set the carb statically with an ohm meter but couldn't get a good reading. I will try with a battery and light to see if this works better. With the setting I did (although questionable), I can report that I see a noticable difference in the engine's behaviour. I am busy for the next few evenings but will get on it soon to see if I'm on the right track.

Thanks for the advice. I will keep you posted.
 
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