So I've got the rebuild pretty well smoothed out except for one little bug on the SDS. We talked with the guys at SDS and here's the situation.

I usually warm my car up about 5-10 minutes before driving. 75 2.0 now rebuilt to 2.7 (as some here have followed). I drive about 15 minutes to the grocery store and go in for about 10 -20 minutes and come back to restart and it starts but doesn't want to idle. Tends to cough and die out. SDS says air cooled engines have this problem with the system as the gas in the chamber evaporates out. I start it up and do a bit of pumping on the gas to keep it running (as suggested by SDS) and by the time I drive to the 1st stop light (maybe a minute or so it then has smoothed out and idles fine.)

I'm not using a stock intake. It's a Japanese Celica intake and we tried adjusting the air mixture a bit but to no avail yet. Also am going to get a CHT guage and oil pressure guage soon so I don't have that info yet. It will come with time. But, I don't think there's any serious overheating going on there.

Anybody got suggestions?

Tx
Eddie

FI or Carbed?

If FI check the cht sensor and the wire leading to it first!

If Carbs .....

Sorry bout that I didn't state it properly.

SDS says that fuel vaporizes at the injectors because the injector is more of a solid mount and air cooled engines run warmer. This is a known issue they have with SDS and air cooled engines.
btw, It's a 4cyl.

The fuel vaperises in the cyl?? I'd have my doubts about that. Your not dirving the car far enough to make that happen and the engine bay temps aren't hot enough.

Where is the inj. located in relation to the head?

When you pumped the gas to keep it running, did it help?

How long did it take for the engine to recover and go back to normal idle?

It sounds like you are in need of a little afterstart enrichment adjustment.

How does SDS measure the temperature of the engine, both in terms of intake air and the "coolant" temperature? On a water cooled car, usually the coolant temp determines enrichment for cold start and warmup. On an aircooled car it is less obvious how to measure and apply that temperature. A lot of the megasquirt guys (including me) use the stock CHT sensor as a coolant input to the megasquirt, what does the SDS use?

If the engine temp isn't being accounted for correctly then the SDS might be assuming every start is a cold start, or something like that.

jeff

my system has sensors in the intake, exhaust and head temp

Read the info at www.sdsefi.com
I'm no expert on all this and usually have a mechanic do the technical jobs. I believe it's taking sensor readings from my cht and intake.
Eddie

Do you have a 02 sensor?
If so what is your AFR at the time of restart?

If you are using the stock CHTS for your WU enrichments is it working ok?

Do you have a way to see if SDS is reading the CHTS when you return to the car from the store? this will play a major role on restarts

The IATS is a small enrichment for the engine BUT if SDS is not reding it right , it can throw things off a bit

I would still suspect you are off on the afterstart enrichments.

If you warm up the car for 5-10 min and drive for 15 min then let it sit for 20. the engine is should stay warm enough to NOT use the CHTS to refer to. which takes you to the ASE.

The ASE can be a tricky thing to find the right settings, it MUST be set right or your type of prob. will arise.

Too much ASE= flooding

Too little = lean starts

What are you using for an aux. air bypass?

If this is activated too low it will cause a lean condition and also cause hard starting. If it's the stock 914 Aux. air and is faulty , they tend to lag and only operate on the engine bay temps. which take a while to make it operate.

I would venture to say that air cooled engine head teps DON'T operate much higher than water cooled engines ( I may be and probably am wrong) but with the AC stuff we alway's measure head temps because we have no other good point for measuring engine heat. A WC engine has water temp to measure from.

So saying the fuel vaporses in an AC engine more than a WC engine........ maybe, maybe not!!

I would say the engine bay temps are higher in my truck than my 914.

With my MS you can program the ASE's which i'm sure is possible with SDS.

Good luck, Keith

OOPS! just saw your last post, looks like you have to take the mechanic to the store next time. LOL

Thanks Keith,
Actually the mechanic had it over the weekend and experienced the problem too. He called the guys at SDS and they explained what I posted up top about the fuel vaporizing (possibly minor vaporlocking) and said the air cooled engines do tend to have this issue.
I think it will be a simple tweek and have had a response on the other board about it too.

Appreciate your info!
Eddie

If you have control of your fuel pressure ramp it up to about 45psi. If not, get control!

That will make it richer across the board, it might make the problem worse.

OK,
You have a Celica intake (show a pic of both the intake and the Injector placement)

the Fuel evaporates out of the chamber....what chamber are we talking about here?

The Stock injectors mounted in the Stock fashion (rubber tips and rubber holders) dont touch metal for a REASON....
The reason is heat transfer to the injector...think about it.

So, show a few pics and I bet if you think about the injectors touching metal, the fuel lines touching metal, the fuel pump and the fuel regulator touching any part of the heat sync we call an air cooled motor...you will find a good mechanical solution.

You need to isolate the fuel system from ANY metal so there is little if no heat transfer to evaporate the fuel.

Jake uses this SDS system with Stock intake, Stock runners and Stock plenum with no issues.
I suspect a part or several parts of the system are heat up the fuel to much prior to the FI....and the FI is touching something like the head or the intake at the metal part of the injector body...

Rich

The injectors are stock 2.0 injectors and nothing is much different from stock other than the intake and SDS. No part of the system is touching metal that we could see.
Click to view attachmentClick to view attachmentClick to view attachment

That is about average for EFI systems. They run high pressure to keep the fuel from forming vapor. It sounds like vapor lock to me...

[quote name='ConeDodger' date='Feb 1 2008, 07:10 PM' post='993166']
[quote name='jkeyzer' post='993140' date='Feb 1 2008, 05:38 PM']
It sounds like vapor lock to me...
[/quote]

That's what I think.

Fuel line routing in the engine bay, can you show details?
Are you still using the stock Fuel pump?
Are you still running it the same way (return to tank at low pressure)

I cant see the line that goes from the passenger side fuel rail over to the pressure regulator and to the fuel rail on the drivers side.

Cold start valve? where is that?
While vapor lock can and does occur, if you are using the stock injectors as shown, you are looking in the wrong place.
What is different?
Is the fuel pressure at least 28 pounds?
Routing of fuel lines
Cold start and temp sensors
SDS needs two sensors, what are you using for these and where are they located?

When you stop the car after a short trip it actually heats up...depends how long you sit.
So, you could have a cold start issue (cold start injector thinks its cold and floods motor)
You could have a temp semsor issue (SDS thinks the motor is to hot, leans mixture to a point that it will not start)

Rich

The reason they run 43.5 to 45 is to get good fuel atomization.

Higher Fuel pressure WILL cause a rich condition accross the board. The 914 runs at 28-29 psi due to the size of the inj's.

Raising the FP to 45 psi WILL raise the flow rate by approx 150cc/min.

If it's vapor lock, That engine is running screaming hot and you have WAY more probs. than restart

This is a ASE prob. and should be easily fixed by adjusting that mixture. If SDS say's that this is a common problem with the AC engines, they should also be able to tell you how to fix it.

I will say one thing, I don't have this prob. with MS