My PMO ITB Project

[scarceller]

Trog,

That's real nice for idle control. Here are some suggested values:

In my car if cyl head temp is below 90F I idle at 1400RPMs
Then from 90F to 150F I idle at 1300RPMs
Then once warm at 170F I idle at target, in my car 920RPM

Then for idle control via timing:
If idle drops below target advance timing 5deg
If idle goes above target retard 5deg

The 'advance timing if idle drops' is very helpful when you return to idle (throttle closes) it helps get rid of that nasty idle dip that many of these cars have.

Real cool,
good luck

[scarceller]

Trog,

One more tip, I was very surprised to find that at cold start (CHT below 60F) my AFR is in the 10.0 to 10.5 range. I was most surprised to find a mixture that rich, but these cars need it at cold start.

I also found that mixtures not rich enough at cold start cause these engines to hunt at idle.

Check out this post from me:
Wide Band O2 + data logger for 84-89 Carrera
It shows you what my cold start AFR looks like on a nice graph. Notice AFR vs CHT on the graph

Hope this may help you as you setup cold start.

[Trog]

Originally Posted by scarceller

Trog,

One more tip, I was very surprised to find that at cold start (CHT below 60F) my AFR is in the 10.0 to 10.5 range. I was most surprised to find a mixture that rich, but these cars need it at cold start.

I also found that mixtures not rich enough at cold start cause these engines to hunt at idle.

Check out this post from me:
Wide Band O2 + data logger for 84-89 Carrera
It shows you what my cold start AFR looks like on a nice graph. Notice AFR vs CHT on the graph

Hope this may help you as you setup cold start.

Good data! However I have another issue at cold idle. I need to design a method to crack the throttle to a pre-set position at cold start. Currently, I have to feather the throttle to keep the engine running until it warms up. I could use a manual choke-cable, but I think I could come up with an electro-mechanical way of setting the throttle position in relation to the CHT. Some sort of servo motor driven off a signal from the CHT. Of course it would have to disengage at operating temperature, but I could do that mechanically through the linkage design.

[toddu]

Huh.... they spelled "to" wrong. "if the idle speed is to low".

Todd

[MrPerkles]

Trog
Being as you are using the mesh filters where have you mounted your air temp sensor ? I am having a set of ITG socks made and not sure where to mount the air temp sensor,is it important it goes as close to the intakes as possible ?

[Trog]

That's quite the coincidence. My new air filters arrive today. The wire mesh filters are fine for show and shines, but for everyday driving, nothing beats a proper filter.

That being said, I relocated my ambient air temperature sensor to the area just below the rear wing. It seems to work fine here and accurately reflects ambient temperature conditions.

[MrPerkles]

ahh cool idea (no pun inteneded) ,ITG is just down the road from me and I was about to pay an extortionate price for some filters and baseplates and they very kindly offered to make me a single filter sock for each bank to suit the Jenveys at half the price.
What filters are you going for ?

[Trog]

Originally Posted by MrPerkles

ahh cool idea (no pun inteneded) ,ITG is just down the road from me and I was about to pay an extortionate price for some filters and baseplates and they very kindly offered to make me a single filter sock for each bank to suit the Jenveys at half the price.
What filters are you going for ?

I'm using the PMO K&N filters that compliment their ITB's. The exception being that rather that using the rain-shields that were included, I opted to purchase their "Racing-Flat-Lids". The only issue with fitment is sourcing wing-nuts that fit the 12-24 threads on the mounting studs. Looked everywhere, but nobody around here seems to carry them in that size. In the end, I purchased stainless wing-nuts with a 8-32 thread, drilled them out, and re-tapped them to 12-24. Broke 3-taps...damn!

Looks like the roads are clearing up around here, so I'll be out shortly to resume my tuning efforts.

[dfink]

It would be really nice if you would just place perhaps a dirty towel or maybe a used tissue in the picture when you post. That engine compartment is just to friggin clean.

In response you your idle condition. I have the same problem and have thought of perhaps a fairly easy fix. Use a solinoid valve to open an airbleeder on the MAP line to the engine. The valve could be controlled by one of the GPO circuits and once set should not have to be adjusted. Just use it to bleed in a little additional air ajust the mixture setting with the warm up enrichments and you should get increased idle speed. Kind of a fixed ICV. Would be easy enough to test the feasibilty by simply putting some sort bleed hole on the line exiting the MAP manifold. I think you would still be able to control the mixture using the blend feature. Just a thought.
I had used one of the heater controls to facilitate a manual adjust until my throttle linkage broke while on the dyno and I had to disassemble to get back running. That worked pretty good. It was just a simple slider that went on the throttle linkage wire that runs from the tranny bell crank to the engine bell crank. If you do the bleeder remember to put some sort of filter on it. There are small sintered filters that should work.

[TimT]

In response you your idle condition. I have the same problem and have thought of perhaps a fairly easy fix. Use a solinoid valve to open an airbleeder on the MAP line to the engine. The valve could be controlled by one of the GPO circuits and once set should not have to be adjusted.

Guys don't make this more difficult than it needs to be..please don't be silly.. we have a bunch of ITB cars under our belt, none have any sort of ICV solenoids etc...

The idle is controlled simply by zero throttle maps.. coolant maps etc...

Look into your software....

I can go into the shop and turn the key on an 800hp ITB car which has 2 injectors per cylinder.. and it will burp..cough a bit then run steady...

keep it simple...

[dfink]

Originally Posted by TimT

Guys don't make this more difficult than it needs to be..please don't be silly.. we have a bunch of ITB cars under our belt, none have any sort of ICV solenoids etc...

Well ya see there is the problem. You know what you are doing and we are just plugging away best we can. The electromotive doesn't really have a zero throttle map. It is based off of manifold air pressure and if that is not stable then you can blend in throttle position. There is also a coolant enrichment and an intake air setting then there is the User adjustable pulsewidth and pulsewidth offset table settings you also have a warmup enrichment and start enrichment. Problem with startup enrichment is there is a fixed 1 second and a fixed 20 second and a temp based 1 second and temperature based 20 second and then there is the time lapse fading enrichment and of course the acceraltion enrichment for both throttle position and manifold air pressure lets not leave out the volumetric efficiency table or the deceleration fuel cut.
I think I am in the same boat as trog is. The only thing that makes any sense is adjusting the V/E table to make the thing run decent. Any attempts to get a zeroed out V/E table generally have resulted in either super lean conditions at WOT or super rich conditions everyplace but WOT. For sure I know I don't see how to make it all work perfect especially when you only have those first couple of minutes to make the adjustments to the computer while just trying to keep the thing running. Only way I have found to keep it running is by giving more throttle. When cold it idles 200-300 rpm slower than warm. By the time I can work the computer it is already too late. Don't know if this is trogs situation also but appears to be. Like most if we can't make it work we look for ways to do it. The air bleed idea is the result of trying to simplify a complex set of conditions using familiar means. Namely carbs. On cold start the throttle was open further and choked to increase fuel and air to make the engine run when cold.
I hope to get an assistant to help adjust the computer and get things closer on startup but once you have made an entry you are stuck for at least that attempt. And which of the 20 settings do you adjust for this 2 minute drill. Starts and runs great after initial warm-up. You can say just go set it correctly and all will be fine but that is easier said than done. For some reason there are alot of cars with idle control valves I guess they were all just being silly. Sorry but the post was not very helpful and sounded like more of a slam than anything else.

[Trog]

My observations, and VE table settings confirm your observations. In addition, I've also thought about using one of the programmable channels in the TECgt to energise a solenoid. However I believe that bleeding air into the MAP line will impact the MAP signal with negative results. Rather, I've been thinking about using a power door-lock plunger to pull on the throttle, thus opening it a predetermined and repeatable amount. When the CHT exceeds set-point, the plunger would de-energize.

[MrPerkles]

Trog sorry more questions:
What /b injectors did you go for in the end ? and how important is injector sizing ,what are the effects of choosing under or over size injectors ?

[TimT]

I haven't used the wintec software in quite a while so I'm a little fuzzy on all its features.

What the zero throttle map does in Haltechs software does is allow you to tune the idle, with no MAP correction.. The idle load is based on TPS, when the throttle returns to zero.. you adjust he idle using injection time and timing advance.. There are also warm up maps, start maps, voltage correction maps..

Is do you think you could do something like that with wintec? Instead of blending map in, blend it our at and near idle.?

For sure I know I don't see how to make it all work perfect especially when you only have those first couple of minutes to make the adjustments to the computer while just trying to keep the thing running.

Cold start is difficult.... especially the COLD we have had the last few weeks...
Data log your starts... its really hard to keep up with all the adjustments you have to make..

[TimT]

Sorry but the post was not very helpful and sounded like more of a slam than anything else.

Sorry the only critique was to say keep it simple.. no slam intended at all... apologies if it sounded that way...

[TimT]

and how important is injector sizing ,what are the effects of choosing under or over size injectors ?

If you use a grossly oversized injector, you may never be able to tune your idle well. Choose a too small inject and you wont be able to supply enough fuel... the injector might be open 100% of the time and still not flow enough fuel..

[MrPerkles]

cheers Tim
anyy idea where i should be with an Injector size for a carrera 3.0 with 48mm taper jenveys,dc40 cams

ps dont you sleep ?

[CruiseControl]

MrP
Suggest an injector with a flow rate of around 400cc/minute.

do a google search for "Stan Weiss Fuel Injector" or try the following:
http://users.erols.com/srweiss/tableifc.htm

Lots of usefull information.

Paul

[MrPerkles]

Originally Posted by CruiseControl

MrP
Suggest an injector with a flow rate of around 400cc/minute.

do a google search for "Stan Weiss Fuel Injector" or try the following:
http://users.erols.com/srweiss/tableifc.htm

Lots of usefull information.

Paul

4OOcc/min is close to 36 l/b which is what I have so should be ok,great info Paul
Get yourself over to europe for a Lemans trip someday and I will buy you a beer

[scarceller]

Originally Posted by MrPerkles

cheers Tim
anyy idea where i should be with an Injector size for a carrera 3.0 with 48mm taper jenveys,dc40 cams

ps dont you sleep ?

I have done extensive tuning in the Carrera 3.2L Motronic system and based on what I see in the 3.2L I would simply use a 24lb injector about 250cc/min I see no need to go any bigger in the 3.0 car.

Trog, is also correct: if you go to large you will have a hard time getting idle correct because large injectors are designed to deliver large volume of fuel and has a hard time delivering small idle volume that's needed by a 3.0L car.

Bottom line is that the 3.2L car uses a 24lb injector and it idles well and is not fuel deprived at WOT.

If you are looking for lo-impedance injectors (like the stock Carrera ones) I suggest the Bosch '0280 150 364' it is a perfect match to the stock '0280 150 158' but can be had for about $25.00 each. Keep in mind these 364s are lo-imp.