mapped - high compression - hard to start

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smckeown
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mapped - high compression - hard to start

Post by smckeown »

I never used to have any issues when the engine was 11.25 compression; it used to start on the button. But since going to 12.3 and fitting a diesel starter motor, it's very hard to start (over 20 start attempts), and it's been professionally mapped too. So before i investigate a racing starter, do these maps look ok to help it start ?

Starting issues and lightweight racing batteries do not mix :(

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Just remembered the starter is 2nd hand..so another solution is to get a reconditioned Peugeot 405 diesel starter..thoughts ?

Sean
205 8v Track car
Colin Haggett
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Re: mapped - high compression - nighmare to start

Post by Colin Haggett »

I would look at the starter motor in the first place, also check all electrical connections, earth strap etc. Might be worth trying the old starter motor? I take it is turning over slowly?
Darrian T90
smckeown
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Re: mapped - high compression - nighmare to start

Post by smckeown »

seems to turn over fast enough. Seems to get slightly more likely to start the more you try (ie getting warmer). Also easy start makes it run for a few secs. That's why I think it maybe map oriented
205 8v Track car
Colin Haggett
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Re: mapped - high compression - nighmare to start

Post by Colin Haggett »

Where does the ecu pick its power from? could be voltage drop problem on starting.
Darrian T90
smckeown
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Re: mapped - high compression - nighmare to start

Post by smckeown »

Colin Haggett wrote:Where does the ecu pick its power from? could be voltage drop problem on starting.
ok i'll check that out. I'm actually making an ECU change in a few weeks, so one of my tasks is to work out how the current setup has been installed. I know the fuel pump is via it's own relay, so i'll check how the coil and ecu get their power.

Should be able to look at this in the morning
205 8v Track car
Guy Croft
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Re: mapped - high compression - nighmare to start

Post by Guy Croft »

You say it spins over easy but does it struggle to turn when it fires? Then in that case my 1st guess is over-advanced - I suggest you reduce your presets as follows:

throttle posn 0: go 5 deg adv for entire speed range

throttle posn 1,2: go 10 deg advance below 1000 rpm.

See if it makes it easier. You can feed in a bit more advance while it's running, if she's a bit rough, then test again.

2nd guess - if it starts well on Easy-Start, it's a sure sign it's way lean. I ran a diesel once on a whole tin of the stuff but as soon as it was empty the engine stopped, turned out to have a blocked fuel line to the Bosch injector pump.

GC
DamirGTI
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Re: mapped - high compression - nighmare to start

Post by DamirGTI »

Hello !

I don't know which type of ignition system you have , but I've had similar problem on my 11.1CR 205 GTi engine , after a few weeks of tearing the engine apart i found that it was the ignition amplifier which caused that hard/difficult starting .
However it wasn't a duff amplifier it was a good one , also i made one test - I've tried full bag of different brands of ignition amplifiers - Bosch , Valeo , Ducellier , Magneti Marelli , Lucas etc. all the same part numb. but different brands , and there was some noticeable difference in between some brands of the ignition amps regarding on how the engine starts (especially from cold) , accelerates and some differences in throttle response ... Anyway I've found that my engine preforms the best with an Magneti Marelli ignition amp. but unfortunately with this one cold starting is the most difficult !

It looks like one amp. is saturating the coil better than the other .

Regards !
Damir
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SteveninNI
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Re: mapped - high compression - nighmare to start

Post by SteveninNI »

check the position of the tooth edge on startup.. some ecus use this as a means of reference for ignition timing until the engine starts.. IE DTA will use 1 tooth or 2 etc depending on what you select.. obviously on a 36tooth wheel this is equal to 10 or 20 degs on starter.. I never use more than 10.

next- if it fires up more easily with a spary of easy start then it needs more fuel in the startup map. Do a data log with a fast acting lambda meter to ascertain this if you dont like the easy start method... i know its crude but time in my workshop is everything!.

Also -aftermarketmanagements need a battery that is well up on the charge. If it goes down on the starter they tend to still fire the inj but notthe coil resulting in fouled plugs.

Been ages since i did a KMS system here on dyno so cannot remember the software exactly so sorry i cannot be of more help.

Steven
petert
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Re: mapped - high compression - hard to start

Post by petert »

I agree with Guy. There's way too much advance on the 500 and 800 map. If the throttle was closed (0%), it would be trying to start with 19 degrees, as cranking speed is less than 500 and thus it would look up that part of the table. There's also too much advance on the 1000 map.

ie

500 - all 5 degrees
800 - all 10 degrees
1000 - all 13 degrees

It needs smoothing out in other areas too. For example, at 2000 rpm, it jumps from 10.9 to 33.8. Too low and too high for that condition. Whoever did the mapping should have spent a lot more time sorting the basics out, rather than just concentrating on full load situations.
smckeown
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Re: mapped - high compression - hard to start

Post by smckeown »

ok so an update here.

This was just before I was planning to remove the existing ECU (KMS) ready for the new DTA ECU.

I didn't alter the map on the basis that with a new battery I was able to get it started but wth difficultl. It would take about 20-30 attempts to start, and I got the uneducated impression is was linked to water temp. The first 10 attempts would be unfruitful in that it would catch momentarily but then die, not actually starting really. Then say attempts 10-20 it would start but would only run less than a second. At the end of say 20 attemps it would actually start. It was exactly the same over the 6 or so time sI needed to start it before the ECU was removed.

So the problem was not resolved per se. I only needed to get it tio start a few times so I could run in the new rings before a new ECU was going in and then straight onto the rollers for mapping.

At the same time I also added a new starter and that turned the engine over quicker which also helped things.

I did get a patched map from a known mapper (the guy who's going todo my DTA) and his map advanced the the ignition about 3 degrees on load site 0 to try and see if that helped. It seemed to make it worse
205 8v Track car
Walezy
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Re: mapped - high compression - hard to start

Post by Walezy »

It looks like you do not have afterstart enrichments and warmup enrichments set up correctly. I do ot know if your ECU has those options but this is what I get on my engine when it is too lean during startup. I run Megasquirt 2.
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