PDA

View Full Version : Mechanical Issues that prevent Good Tuning



WeathermanShawn
April 19th, 2011, 04:17 PM
In-Memory-of-Shawn-Sankey (http://forum.efilive.com/showthread.php?16849-In-Memory-of-Shawn-Sankey)


TUNERS CHECKLIST

1. General Checklist
□ On a cold start, just prior to starting, IAT and ECT should be very close, within a few degrees of each other
□ MAP should read same as barometric pressure
□ MAF should read zero airflow
□ Battery should be fully charged and functional

2. General Maintenance
□ Replace air and fuel filters annually
□ Check oil level and replace dirty oil
□ Clean MAF with approved electrical cleaner
□ Check PVC system
□ Ensure spark plugs and wires are operating normally
□ Check for manifold and exhaust leaks
□ Replace Narrowband O2 sensors at least every 60,000 miles

3. Injector Tuning
□ Ensure your injector data is accurate
□ Check fuel pressure and replace the fuel pump/wiring, if necessary
□ Ensure you have the correct IFR slope (sloped vs. flat) and that it matches the FPR (un-reference vs. referenced)
□ Check for fuel leaks anywhere, which this is a fire hazard
□ Any bad grounds, insufficient wire sizing, and/or poor connections will lead to fueling problems

4. Tuning/Mechanical Issues
□ Ensure you do not have excessive heat-soak. For more accurate readings and consistent fueling, IAT Sensor should be located away from heat sources (like the radiator or the engine itself)
□ Home-ported throttle body can be problematic
□ Ensure catalytic converter(s) is(are) not blocked or plugged

5. MAF & Other Sensors
Good NBO2 in closed loop (i.e. trimming properly) will show these characteristics during steady part throttle:
□ Swinging faster than two (2) complete cycles per second
□ Swinging above 600 mV and below 300 mV
□ Average voltage will be close to 450 mV
□ If they switch slower than three (3) cycles per second, the trimming will lag a little behind
□ If they switch without going above 600 mV or below 300 mV then a DTC will trigger
□ If the average mV deviates significantly from 450 mV then the trimming will be to some unpredictable AFR
□ MAF signal should not show jagged edges or rapid changes in airflow during cruise or WOT. Some oscillation is normal, but it should not exceed 5% per frame (1/10 sec)
□ Wideband Location is crucial. Tailpipe locations should be avoided. Follow the wideband manufacturer’s guidance as to the location and installation. Sensors should be calibrated regularly, including heater calibrations if necessary.


Example of normal operating Closed-loop Scan with Fresh O2 Sensors. (Long-Tube Header Location) Shows NB switching, steady MAF signal, and wideband oscillating normally around stoich AFR.

http://i1126.photobucket.com/albums/l609/weathermanshawn/HeaderHO2.png

Example of why you should NEVER use Stock NarrowBands for WOT Tuning Fresh NB O2's..AFR both 12.62.

1. IAT 90F MV: 872-890

http://i1126.photobucket.com/albums/l609/weathermanshawn/WOT90FIAT.png

2. IAT 64F MV: 929-942

http://i1126.photobucket.com/albums/l609/weathermanshawn/HO2IAT64F.png

5.7ute
April 19th, 2011, 05:28 PM
Good idea for a thread Shawn.
An issue I have come across a fair bit is due to insufficient fuel pressure at the rail, especially on older cars. It has become that common that I always log fuel pressure when dialling in a car these days.

WeathermanShawn
April 20th, 2011, 02:18 AM
Thanks Mick.

Good one. We will add it to our list.

ChipsByAl
April 20th, 2011, 12:13 PM
Its not exactly a mechanical issue, but not having accurate injector information can be a problem also. The transmission\clutch needs to be in good condition before any WOT tuning. The vehicle being due for an oil change or even low on oil can abruptly stop the tuning process. Just some things that need to be checked before starting.
Al

jorge
April 21st, 2011, 01:21 AM
Good one Shawn,
I have always had mid rage knock after playing with tining and fuel presure so on so forth, found its valve train noise.
Jorge

WeathermanShawn
April 21st, 2011, 11:51 AM
Thanks Al and Jorge.

All very good examples that we can use.
Appreciate the ideas..:cheers:

tinindian
April 21st, 2011, 02:24 PM
I agree with Chips - having the correct size injectors is key. Also I found a big difference in my tune after I cleaned the K & N intake filter. I was shocked (and slightly embarrassed) how dirty it was and what a difference it made in VE tables and idle quality.

MECHAN12
April 21st, 2011, 03:38 PM
i am new to the tuning end of it but what i have found out working on cars is if the map shows bad or is giving trouble change the relay in its line first . 2 fuel pressure problems or running lean change the fuel filter
donald

joecar
April 22nd, 2011, 01:21 AM
Air and fuel filters are a periodic maintenance item, they should be changed/cleaned at least once a year.

Many people ignore the fuel filter (out of sight, out of mind).

Small things like dirty filters, dirty MAF, leaky PCV plumbing can really frustrate a tuner... when you see no convergence then you know something is up.

joecar
April 22nd, 2011, 01:23 AM
Another problem is having the wrong IFR slope (sloped vs flat) that does not match the FPR (un-reference vs referenced).

Also, fuel pressure should be checked, and the fuel pump diagnosed if necessary.

And, there should be absolutely no fuel leaks anywhere, which this is a fire hazard.

joecar
April 22nd, 2011, 01:27 AM
On a cold start, just prior to starting:
- IAT and ECT should be very close, within a few degrees of each other;
- MAP should read same as barometric pressure;
- MAF should read zero airflow;

Those are simple sanity checks that are easy to perform (a good habit).

SSpdDmon
April 22nd, 2011, 02:56 AM
Heatsoak is mechanical IMO. IAT sensor location on both forced induction and naturally aspirated engines is key in these cars. If you can keep the sensor away from heat sources (like the radiator or the engine itself), you'll have much more accurate readings and consistent fueling.

redhardsupra
April 22nd, 2011, 03:37 AM
Home ported TB's are annoying. They never cause problems big enough to force people to reevaluate if they need a new one, but the car will never be 'right' either.
Inadequate fuel pump wiring, causes fuel pressure drops but only under load, so unless you're monitoring for it, you're not gonna know what's wrong other than 'not enough fuel' no matter what you do.

But the biggest problem I've seen is when people run low on the IQ fluid in their brain tank...

Mr. P.
April 28th, 2011, 02:15 AM
Improper PCV circuit in boosted applications (i.e. oiling down the intake manifold on WOT).

Mr. P.

Chevy366
April 28th, 2011, 04:45 AM
Something as simple as a low battery can cause anomalous readings , have seen DTC for misfire and all it was was battery was low .
So make sure battery is fully charged and healthy after a implant or rebuild .

Chuck L.
April 29th, 2011, 08:34 AM
Bad grounds, insufficient wire sizing, and poor connections.
I work on older EFI cars such as the turbo Buick. I see the above problems frequently.

Additionally, my injector flow bench reveals some "scary" flow rates and patterns on injs that have been neglected...

366... Liquid detergent is much easier to pump thru them....:hihi:

jorge
April 29th, 2011, 01:41 PM
Hey Chuck, I hear you. I have a 99 Vette that had all types of ground problems.
Nailed it about a year ago.
good one.

Jorge

WeathermanShawn
May 2nd, 2011, 06:12 AM
We appreciate all the responses so far.

I have slowly started adding a summary and examples of a normal operating WB, NB, MAF signal, etc.

I will post the changes to page 1 of this thread.

Feel free to add any other suggestions you have.

Mr. P.
May 2nd, 2011, 07:07 AM
Plugged catalytic converters.

Mr. P. :)

WeathermanShawn
May 14th, 2011, 02:37 PM
Thanks for all the ideas..

I updated page 1 of this Thread and included a short 'Tuners Checklist' in PDF form:http://forum.efilive.com/showthread.php?16139-Mechanical-Issues-that-prevent-Good-Tuning

In no way is this meant to be a total checklist of everything one needs to check prior to Tuning. Its just a start. It is mainly to make beginners aware of the many mechanical issues that can effect tuning.

Hopefully it will at least people more aware..

Thanks again..:cheers:

joecar
May 14th, 2011, 02:55 PM
List looks good :cheers: