EFI VK something very strange happening

[Penrod]

As this is my first post here, i'll say greetings to all.

Enough of that, straight too it.

I have a rather strange thing going on in my '85 VK, I've just rebuild another 202 for it, machined and ballanced crank, a very mild sort of cam shaft, just abit better than standard. When the engine was brand new freash as, and i fired it up for the first time, it literally wound over 5 times and fired and ran. It was good for about 10 minutes. After i went for a short run, and then came to a stop, it just sort of came to a halt and the engine ran out of steam and conked out.

I thought ahha, i have a tight lifter. Pulled off the tappet cover and shimmed up the rockers abit to relieve some preasure.

Started it up, vroom good as smooth idling fast, rattling abit from the loosened lifters. As soon as the oil primmed into the lifters and preasurised, the engine got slower and slower untill it just stoped again. It will run at road speed, very well. It will just bearly idle, and soon as i drop it into gear it just wants to stop.

I have swaped and chaned a couple of computers, i have a new air flow meeter, have changed every vacume hose, rebuilt the injectors, even the head. I am at a loss as to what i can try next.

If anyone has any ideas, atall, or suggestions that i can try, id love to discuss options.

[Penrod]

Basicly, what the problem is, my car wont idle. Being fuel injected, because it wont idle, it wont start. Because it wont start, its very upsetting.

The confusing thing is, when the hydrolic lifters were empty of oil the engine ran perfectly. Soon as the primed the problem started.

[Not_An_Abba_Fan]

Do you have the correct lifters? Once primed are they too long keeping the valves open so you have no compression? Do a compression test and see if you do have compression.

[Tree cutter]

I would say you have less manifold vacuum at idle with the slightly larger cam. Before the lifters fill up with oil the valves will open later and close earlier so your engine will behave as if it has a smaller cam having more manifold vacuum at idle. I am not familiar with the fuel injection system on a VK but if it has an air idle control valve, you could try adjusting it to let more air in at idle.

[Pub247]

how big is your cam? if it is too big the efi system wont work. If it has bigger specs than this it could be a problem.
Valve timing
IN.17/58
EX.63/17
duration
255
260
.50" duration
200
204
valve lift
.400"
.415"
Power range
1400
4200

Also another thing i was thinking is along what tree cutter said regarding the AAV when it closes the idle might be to low and the engine dies have you tried advancing the dizzy a bit and see if that keeps it running? I'm sure you have the base timing set correct.

[cpbait]

yeh from memory they do have a idle air control valve, do you need to tune the computer with the larger cam in one of them?

[mag]

Double posted it

[mag]

As this is my first post here, i'll say greetings to all.

Enough of that, straight too it.

I have a rather strange thing going on in my '85 VK, I've just rebuild another 202 for it, machined and ballanced crank, a very mild sort of cam shaft, just abit better than standard. When the engine was brand new freash as, and i fired it up for the first time, it literally wound over 5 times and fired and ran. It was good for about 10 minutes. After i went for a short run, and then came to a stop, it just sort of came to a halt and the engine ran out of steam and conked out.

I thought ahha, i have a tight lifter. Pulled off the tappet cover and shimmed up the rockers abit to relieve some preasure.

Started it up, vroom good as smooth idling fast, rattling abit from the loosened lifters. As soon as the oil primmed into the lifters and preasurised, the engine got slower and slower untill it just stoped again. It will run at road speed, very well. It will just bearly idle, and soon as i drop it into gear it just wants to stop.

I have swaped and chaned a couple of computers, i have a new air flow meeter, have changed every vacume hose, rebuilt the injectors, even the head. I am at a loss as to what i can try next.

If anyone has any ideas, atall, or suggestions that i can try, id love to discuss options.

If all was new you are suppose to run in the cam about 15-20mins at about 1500-1800 rpm

And If you shimmed up the rockers you've got the later non adjustable head, has it been shaved??

Also you haven't mixed up any push rods from say a 186 have you??

That's all I can think of at the moment

[Pub247]

Mag has made some good points there. Being EFI the rockers on all 12 port heads are non-adjustable. When I put the new and cam in my Vh i ran the cam in for 15 minutes i had also pre primed the pump and new lifters before starting. My head was shaved when i put it on i didn't have any troubles with the rockers.

yeh from memory they do have a idle air control valve, do you need to tune the computer with the larger cam in one of them?

The have an Auxillary Air Valve which is different. It is open when the motor is off or cold when turned on it heats up and slowly closes these are non adjustable. Also it is impossible to re-tune the Ecu in EFI motor as they are an analog computer.

[Penrod]

The compression seems to be fine, all nice and high. Unless My compression should be alot highter than 130 pounds. I dont think it would be.

I would say you have less manifold vacuum at idle with the slightly larger cam. Before the lifters fill up with oil the valves will open later and close earlier so your engine will behave as if it has a smaller cam having more manifold vacuum at idle. I am not familiar with the fuel injection system on a VK but if it has an air idle control valve, you could try adjusting it to let more air in at idle.

I thought this was the case. But why dont the lifters take up the difference and operate normally? Thats why i shimmed up the rockers to take some of the presure off the lifters. Perhaps i could shim them up abit more, so i only have a quarter of a turn rather than 1/2 a turn.

Its entirely likely that i do need to re-tune the air flow meter, ill put it in for a tune up next week or so.

Thanks for all you help and ideas guys.

The cam info is:
lift at lobe: .262"
Running clearance Ex .014" In .014"
Timing Ex Opens: 66 degrees Closes: 30 degrees
" In Opens: 30 degrees Closes: 65 degrees
Lift at T.D.C. No.1 inlet follower: .050"

This info i gathered from the tag that was attached to the cam when i got it. I was told it should produce higher torque.

[Tree cutter]

I thought this was the case. But why dont the lifters take up the difference and operate normally? Thats why i shimmed up the rockers to take some of the presure off the lifters. Perhaps i could shim them up abit more, so i only have a quarter of a turn rather than 1/2 a turn.

When you run your engine the lifters will fill up with oil until there is no gap between the lifter and pushrod. The correct way to put preload on your lifters is to do one cylinder at a time. Get it at TDC then undo the two bolts on the rocker pedestal, next hold the pedestal down with your hand so the rocker arm is just resting on the pushrod and valve then measure the clearance between the bottom of the pedestal and the head. There should be a gap of between 20 to 40 thou. You use feeler guages to measure the gap. If the gap is larger than 40 thou you need to put shims between the pedestal and head. If the gap is less than 20 thou you need to grind a bit off the bottom of the pedestal. When you have the correct gap then tighten the bolts back up.

[Penrod]

Tree cutter wrote>

When you run your engine the lifters will fill up with oil until there is no gap between the lifter and pushrod. The correct way to put preload on your lifters is to do one cylinder at a time. Get it at TDC then undo the two bolts on the rocker pedestal, next hold the pedestal down with your hand so the rocker arm is just resting on the pushrod and valve then measure the clearance between the bottom of the pedestal and the head.

Yep, exactly. I didnt measure the gap, but i just shimmed the Rocker posts untill i had exactly 1/2 a turn out of the retaining bolts. Its too late in the day to go do it now, ill measure the gaps tomorrow and let you know what i find out.

How did the can specs look? I dont know what the standard cam spacs should be.

[Tree cutter]

Your cam is definately bigger than the specs that Pub 24/7 recommends as maximum. You have a bit more lift and a fair bit more duration which will cause you to have low vacuum at idle. Looks like you need to run either a smaller cam or a different computer that you can adjust to suit the cam.

[Penrod]

Tree cutter wrote:

Looks like you need to run either a smaller cam or a different computer that you can adjust to suit the cam.

Interesting, Can i get a different computer to suit such an old EFI system? Can you tell me more?

The cam in question was a beutiful cam in the 186 i had it in before, it would be nice to have the same kind of performance out of the 202. I had no idea that a cam could alter the performance so greatly. Id like to keep using it.

[Tree cutter]

It would be worth talking to someone who sells aftermarket computers and see what they come up with. Your 202 will idle a bit rougher than the 186 did with the same cam because the 202 has a longer stroke. Big cams don't affect short stroke motors down low in revs as much as a long stroke motor.

[Pub247]

A Haltech fuel only would be well suited to the vk. Even one of the older will do well. There would be alot of advantages to an aftermarket ecu. You can get rid of the flapper style AFM which is a good gain in power there.
An older Haltech or something similar could be acquired for about $500 or less.

[Pub247]

HALTECH E6GM ENGINE MANGEMENT SYSTEM - eBay, Alarms Electronics, Car Accessories Tuning, Cars, Bikes Boats. (end time 09-Nov-07 20:09:01 AEDST)
this one here would be a good choice plugs straight into a vn or camira wiring harness.
Get a camira harness and the module off the dissy plus some of the sensors wire it up retune it and it'll be best cheapest option probably

[Penrod]

Thanks all for your help on problem solving my little problem. I've put it down to the fact that the cam im using is not idealy suited to the EFI on a VK. Also the the EFI they put on VKs was just crap to begin with. I had a tune up done yesterday, it seems to atleast idle abit better and start alot better. Id like to see the idle manifold vacume up abit, but im just not able to change the computer at this time. And i dont feel like changing the cam again.

The ideas and help i got here on the forum was greatly helpful, thanks all again.

[davesmonaro68]

A Haltech fuel only would be well suited to the vk. Even one of the older will do well. There would be alot of advantages to an aftermarket ecu. You can get rid of the flapper style AFM which is a good gain in power there.
An older Haltech or something similar could be acquired for about $500 or less.

I'm chasing one of these older ones if someone has one to sell let me no please.
Dave

[vkberlina]

Just a question whats your fuel pressure at idle??

cheers
scott