21 replies to this topic

[eero]

To conclude my issues:

 

A few years back I went to local mechanic who helped me get exhaust gases sorted for MOT. He did this by changing the fuel pressure regulator spring and lower pressure leaned the mixture, getting gases sorted. At the time I really didn't know what he had done, I was really a newbie. And it did the job, the engine ran fine, albeit maybe not at its best. 

 

Now I went back to him thinking he might have an idea whats going on as I knew he had done something. Lucky he still had the old spring, put it back, and all is good. Running really well.

 

The funny thing though, which I don't understand, is that with the hoseclamp I drove the pressure up to 2bar to get the engine running better. Oddly this didn't even affect the fuel consumption, but made world of difference. Removing the hose clamp reduced the pressure to 1bar, which is where it should be, but engine was really struggling. Using the original spring on the pressure regulator spring resulted in the same pressure of 1bar, but engine now runs fine. Don't really understand the dark magic at play here, but it works.

 

[eero]

I finally received my SP ACR a few weeks back. When I first got the reader it immediately showed that inlet pressure was at 86kPa, so no proper vacuum. I replaced all the hoses with 5mm fuel hoses and now all the component tests are reporting measurements as expected and the engine is running quite well.

 

 

My ACR numbers at idle:

• throttle stays constantly at 0.58V, no fluctuation (found this video, where it does wiggle a bit)
   
• pressure 29kPa - 32kPA
• coolant ~92 degrees
• lambda 70mV - 830mV

 

So what remains now is high idle at about ~1100rpm and it seems to be fluctuating a bit too much. So I thought I'm back to the screw, which started this whole topic. As I only had v1 pod I had to order v3 pod with stepper adjustment feature to sort this out. It arrived this week and got to try it today.

 

Only once did I get into the adjustment feature, all other tries it's reporting that the RPM is not stable enough to carry out the adjustment.

 

The one time it continued, the engine revs immediately went up a bit and stayed quite constant (by hearing), and it said to adjust the screw until the step count stopped blinking. But the step count only stayed at 0, and no matter which way I adjusted the screw, and the stepper rod did not move. Was I maybe not doing it right?

 

Could it mean there is a fault with the stepper motor? It does seem to function though, as when turning the engine off I can clearly see it's setting the throttle for restarting.

 

Or could there be something else I'm not thinking of?

 

The odd thing is that one morning a few weeks back the idle did drop to about 900 by my estimation. But by the time I got to the garage to check with the ACR what might have changed, high idle was back. I suspect a really low pressure front with the weather

Edited by eero, 12 October 2013 - 04:54 PM.

[FlyingScot]

Test the stepper motor using the component menu in your ACR. Also check the throttle cable is tensioned correctly with an even gap.
Check the connections to the stepper motor and if you have a multimeter check the coils impedances are the same (from memory it's on here but if not I will check for you as I have a new one in stock).

Re reading your comments it could be you have an air leak and the stepper is unable to reduce it. Check the purge valve hoses, and the inlet manifold for air leaks (one old way is to spray some oil like WD40 carefully at the inlet and see if the idle increases showing it is bring drawn in).

Is the video of your car? Coolant temp of 109C ! and iac of 49C ???

FS

Updated with better clarity!

Edited by FlyingScot, 12 October 2013 - 07:47 PM.

[Fast Ivan]

show us the readings from a cold engine and a warm engine

[eero]

FlyingScot, no, the video is not of my car, it's just one I found randomly on YouTube.

 

Anyways, I have now traced it down to being indeed problem with the breather system, thanks FlyingScot!

 

Started cold today and did actuator test for the stepper motor. By sight it seemed to move steadily and with enough amplitude. Sprocket mentioned somewhere it should move about half a centimeter, I'd say the movement was more like 1 cm. So my thinking was that this was not the issue.

 

Measurements cold, before turning on the engine, outside temperature about 10°C:

• MAP 101kPa
• CTS 9°
• IAT 12°
• Ambient 9°
• Battery 12.2V
• TPS 0.96V
• Lambda 435mV

 

Turned the engine on, still cold:

• RPM 1200 +/- 50
• MAP 34kPa
• Battery 14V
• TPS 0.64V
• Lambda 90 - 840mV

 

At about midway warming up, CTS 70°, RPM dropped a bit, 1100 +/- 25, the rest stayed the same.

 

Warm:

• RPM 1100 +/- 50
• MAP 35kPa
• CTS 90°
• IAT 19°
• Ambient 15°
• TPS 0.62V
• Lambda 75-820mV

 

At this point couldn't make heads or tails of anything - numbers seemed normal except high RPM. So I revved the engine to about 3300rpm and kept it there for about a minute, which should be enough to open up the purge valve.

 

After that on idle:

• RPM 1500 +/- 50
• MAP 29kPa
• CTS 92°
• IAT 24°
• Ambient 17°
• Battery 13.9V
• TPS 0.64V
• Lambda 95 - 780mV

 

 

And the RPM stayed this high for quite some time, couldn't wait for it to drop. So I started pinching the breather hoses with pliers and found one point which did reduce the RPM. (number 11 on http://minispares.co...~.aspx?2~12~117 ).

 

Turned the engine off and let it settle a bit to close the purge valve. Took the suspect hose off and plugged it with the tip of my finger. Turned the engine on and the idle RPM was now about 950 +/- 50. 

 

So seems the breather system needs an overhaul. Right now I clamped all the hose connections I could get to without removing much in the engine compartment and warm idle is around 1000rpm, about 1100 after keeping the engine over 3000 for a minute or so.

 

 

My initial thought was that as the MAP reading was as expected there are no air leaks. Guess I was wrong. Can air leaks only be detected with gut feeling or is there something in the readings that would indicate this?

 

Funny though - one would suspect 20 year old electronics wouldn't be that reliable, but so far it's the simplest things that have been at fault.

[eero]

Followup on my issues - replaced all slimmer breather hoses with armed fuel lines (5mm if I remember correct) after which the ECU was able to maintain a steady RPM which in turn enabled to me to finally adjust the screw with the ACR.

 

Now idle pretty much holds dead on 850 and general running seems to be improved as well. Success!

 

 

Kudos to everyone and yet again - with SPi running issues, start with the vacuum and breather system.

Edited by eero, 17 June 2014 - 02:54 PM.

[FlyingScot]

Thanks for the update Eero, it's appreciated as many posters never let us know how they got on.

Glad it's all sorted and take a pat on the back for being able to use the ACR to set the "idle screw"

FS