Stand alone Engine tuning question.

abec

abec

Wil
I figured Id post this here and see if anyone could give me some ideas.

I am running stand alone fuel management. I was having issues with the car hesitating during initial acceleration on partial throttle, when leaving lights at normal speeds. I countered this by slipping the clutch a bit more. I had the stock TPS installed at the time, which is only useful for full throttle.

I just installed a Variable voltage tps, so I get partial throttle now. I set it up so that the ECU indeed sees the tps correctly. But now instead of having issues on acceleration I am having issues during cruising and staying around 3k rpm. It will stutter when trying to maintain RPMs. It when I disconnect the TPS it goes away, and my original problem comes back.

I can log everything my ecu is doing, TPS, RPM, Injector duty cycle, injector time, air temp, engine temp, ext.

So my question is, what should I be looking for and adjusting to smooth this out?

!UPDATE!
The issue is almost all gone, there is still a slightly noticeable stutter when cruising under 3k rpm. Not even close to what it was doing before though. The small stutter thats left is due to my half done installation of the TPS, which allows it to have some slight movement and causes around a +/- 5% jitter in throttle position while moving. Once I get the tps hardware I need the tps should be on there rock solid and this should go away.
 
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Hmmm

Hi Wil,

I'd say with the info you provide, it is impossible to make a sensible comment.
I would connect a wide-band O2 meter to really see what is going on, then reprogram as needed.
 
Ulix said:
Hi Wil,

I'd say with the info you provide, it is impossible to make a sensible comment.
I would connect a wide-band O2 meter to really see what is going on, then reprogram as needed.
Click to expand...

Ya, I am ordering up a wide-band O2 this week.

What info could I provide that would help other then the air fuel ratio. Or do I have to wait for the O2 to get here.
 
Are you running a TPS and the AF sensor at the same time? Do you have any internal engine mods to the car?

The TPS and MAF can give conflicting info. The AFS can be seeing some pulsing which the TPS wouldn't thus creating an issue. I know some either run one or the other but not both. The TPS works better in combination with a wide band O2 sensor for cars with wilder setups.
 
kmead said:
Are you running a TPS and the AF sensor at the same time? Do you have any internal engine mods to the car?

The TPS and MAF can give conflicting info. The AFS can be seeing some pulsing which the TPS wouldn't thus creating an issue. I know some either run one or the other but not both. The TPS works better in combination with a wide band O2 sensor for cars with wilder setups.
Click to expand...

At the moment no AF. The engine is big valve & 10:1 compression.

I spent all night reading the manual for my ECU. It said basically the same thing.

I found out there is a setting that adjusts fuel enrichment on throttle movement that uses the tps, which I believe is what I need to use in order to fix the issue I have when I didn't have a tps. After that I need to disable most of the other TPS functions, as they are not needed.

I logged a bunch of data, is it normal for the injector duty cycle to be at 0 while cruising?
 
You need to know what your A/F ratio is. Also are you running speed density or alpha-N? I assume you are running speed density but if you aren't then not having a TPS will cause major issues. Also, some ECUs allow a combination of speed density and alpha-N. If it's set up that way there could be problems with the setting causing issues with the TPS.

The injector duty cycle can't be 0 with the engine running. However, You will get 0 on decel if you have it set up for decel fuel cut.

It sounds like you need to start by building a decent A/F table and if your ECU supports it set it to alter your VE table using a WB sensor. Once the VE is dialed in pretty well then try to figure out your problem if it's even still there.
 
Matthew said:
You need to know what your A/F ratio is. Also are you running speed density or alpha-N? I assume you are running speed density but if you aren't then not having a TPS will cause major issues. Also, some ECUs allow a combination of speed density and alpha-N. If it's set up that way there could be problems with the setting causing issues with the TPS.

The injector duty cycle can't be 0 with the engine running. However, You will get 0 on decel if you have it set up for decel fuel cut.

It sounds like you need to start by building a decent A/F table and if your ECU supports it set it to alter your VE table using a WB sensor. Once the VE is dialed in pretty well then try to figure out your problem if it's even still there.
Click to expand...

Speed density, not Alpha-N. I have a 2 bar MAP sensor installed, the fuel map is tuned to the manifold reading from that MAP sensor.

I do have fuel cut above 2k RPM, but its showing 0injDC when the engine is in a obvious cruising state. So maybe the fuel cut is to sensitive or the reading is wrong, I need to run some more logs today and see whats happening.

The ecu can indeed do that. I am ordering a WB 02 controller & sensor either today or tomorrow.
 
What camshaft?

You may have to run only on TPS without the Map Sensor if you are running a cam shaft 40-80 or hotter. The Pulses of Manifold Pressure will throw the fuel map way off.

Look at the Map Sensor guage on the screen and if it is not steady, then you have to be on TPS only.

Even with a narrow band sensor you can see if you are too rich or too lean. Just remember with a wide band if you are way to rich it will show lean.

What system? MegaSquirt?
 
TonyK said:
You may have to run only on TPS without the Map Sensor if you are running a cam shaft 40-80 or hotter. The Pulses of Manifold Pressure will throw the fuel map way off.

Look at the Map Sensor guage on the screen and if it is not steady, then you have to be on TPS only.

Even with a narrow band sensor you can see if you are too rich or too lean. Just remember with a wide band if you are way to rich it will show lean.

What system? MegaSquirt?
Click to expand...
Its a Haltech F10X

Stock cam. The manifold pressure is fairly solid.

Here is an interesting comparison.
black = RPM
Blue = Manifold pressure
red = injector timing
graphs.jpg


I am thinking the throttle pump settings are to high. The ECU is in MAP Sensor mode, with both zero throttle and full throttle maps disabled.

I am finding it odd that my tuner said I needed a TPS. At the moment I can't really find a reason as to why its needed. So at the moment I think he just did a half assed tune.
 
Enrichment.

If I am reading this correctly, the fuel is dropping off with the manifold vacuum.

The enrichment settings for throttle position can be a bit tricky. And you may find that your are really running on the position change or rate of rise for enrichement. With the stock camshaft you can run on MAP Dot without problems. You don't need TPS Dot at all for that camshaft. If the injectors are dropping off, increase the inrichment, not sure how it works on your system, but go to your VE map and bump it up a bit in the 3000 RPM and corrisponding MAP values. You look lean to me and the engine will just starve for fuel.

Ya Looked again in TPS you are getting enrichment pulses that need to be backed off. Way to rich.

TonyK.
Grimsby Ontario Canada.
 
I am looking at the default throttle pump settings, they work in Increments and decay. Default is 1.2% increment and .7% decay at 3k rpm, the tuner put it at 20%. I think he was adjusting it without realizing the stock tps was a 2 position tps. UGH putting that back to default, and going to drive around and see how that works.
 
Sounds like your are on track.

20% that explains the huge spike.

I made the same mistake on my car in TPS DOT and backed the VE table way off. I had the Acclerator Enrichment set up too sensitive. .2 ml volt I think. Anyway when I finally got the car cruising the engine would just drop off power. Well that is because the throttle wasn't moving and pumping fuel in as an enrichment.

Best of luck, you should play with it a bit and see some good performance in short order.

TonyK.

Grimsby Ontario Canada.
 
TonyK said:
20% that explains the huge spike.

I made the same mistake on my car in TPS DOT and backed the VE table way off. I had the Acclerator Enrichment set up too sensitive. .2 ml volt I think. Anyway when I finally got the car cruising the engine would just drop off power. Well that is because the throttle wasn't moving and pumping fuel in as an enrichment.

Best of luck, you should play with it a bit and see some good performance in short order.

TonyK.

Grimsby Ontario Canada.
Click to expand...

Thank you very much! Hopefully by summer I am an expert and I can tune my car when I go turbo... muhahahahaha :devil:
 
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