Need 70% PWM to run w/ flyback board

Kirk Carleton · Post by **Kirk Carleton** » Thu Jan 05, 2006 10:33 pm

1983 VW GTI 1.8L stock
Injectors 19.3 lbs. 2.6 ohm (P/N 0-280-150-812)
MS I V2.2 code 3.0
Megatune 2.20

I have read through the manuals and have searched this forum under "flyback" and have scanned over 400 postings. and the information I get that if the PWM has to be set to 70% with a fly back board then the board is not working. Roger has been very helpful in helping me with some other issues (see: http://www.msefi.com/viewtopic.php?t=14555), but asked me to repost this flyback problem.
I need 70% to get started cold (15*F) and once it is running it will idle poorly at 62%, when it is warm it will restart as low as 65%.
I have rececked all the components on the board and they are installed correctly and the correct values. I did substitute the FR302DICT-ND (D100 and D103) with a 1N5401, but by looking at the spec sheets I believe this is OK. I have checked all the solder joints and verified that the Q102 and Q105 are isolated from the heat sink. All the flyback components have been removed from the MS board and the six wires to connect the two boards are correct. The wiring harness is in good shape and has been checked for resistance and checks out good.
I have used a scope on the injector outputs on both the stim and on the car when it is running and it is doing what it is supposed to - I have the PWM threshold set at 1.1 ms, the scope shows a 1.1 ms pulse followed by susequent 70% pulses for the remainder of the PW. The scope shows that the PW is at full system voltage (about 13).

Are there any other tests that I can do?

After a 20 min. drive at cruise speeds the injectors do not feel hot to the touch.

What are the consequences of operating under these conditions??

Any help with this will be greatly appreciated

Thanks
Kirk

renns · Post by **renns** » Fri Jan 06, 2006 11:15 am

Bump...any flyback board experts in the house?? Anyone else running PWM %'s in Kirk's range?

Kirk Carleton · Post by **Kirk Carleton** » Sat Mar 11, 2006 2:54 pm

I have driven about 5000 kms since the last posting and still need 70% PWM to run. Today I have replaced the FETs IRFIZ34 (Q2 and Q7) no change. Then I replaced the FET driver IXDI404PI (U7) no change. On the flyback board I replced the Q101 and Q104 from a TIP32C to aTIP42 and there is no improvment.
When I last posted I thought I had some ignition noise but it is actualy injector noise, but it does not reset the second count.
Can a capacitor be added to the flyback board to iliminate the injector noise??

It would be very helpful if anyone has any new ideas to try

Thanks
Kirk

keithmac · Post by **keithmac** » Sat Mar 11, 2006 3:22 pm

I run 500cc/min HighZ injectors on MS1 - Extra and the idle`s fine, if you can`t locate the fault have you thought of running different injectors? Idle shouldn`t be a problem on 20lb`ers if that`s the main reason of using Low impedence injectors?

slow_hemi6 · Post by **slow_hemi6** » Sat Mar 11, 2006 6:20 pm

Hey Kirk, Still no luck then.If I were you I would get those standard recovery (ie slow switching) 1N5401 diodes out of there and go with a fast recovery diode like the FR302DICT.The 1N5401DICT is listed as fast recovery and maybe you have those but perhaps not. Still the flyback circuit needs to switch very quicky.

Kirk Carleton · Post by **Kirk Carleton** » Sun Mar 12, 2006 9:40 am

Thanks Luke - I'll try that when I get the parts.

Kirk

Kirk Carleton · Post by **Kirk Carleton** » Sun Mar 12, 2006 10:22 am

Hi Luke

As before Digikey does not have stock and the data sheet has a note on it "not recomended for new disign Please use PR3001G - PR3007G". Has anyone tried a PR3002G? I have attached both data sheets, they look close to the same.
Any input is appreciated

Thanks Kirk

John L. · Post by **John L.** » Wed Mar 15, 2006 8:10 am

When I had this problem I had left out the two top most resistors on the board, which are for flyback. Just a thought in case you haven't checked everything like that.

I'm having injector noise problems also, well, no problems now that I put a noise filter inline with the MS, but it was resetting my LC-1 and now it's not, I was having spikes with only 4 V at times and lots of noise in general. An Advance Auto audio noise filter will work, but it's a little overpriced for what it is inside, you could just make a filter.

Kirk Carleton · Post by **Kirk Carleton** » Tue May 09, 2006 10:54 am

Thanks to a fellow squirter (63vette) I have found that when I used EasyTherm that I loaded a oldeer embedded code that does not support the Flyback board. I now have V2.986 loaded and the flyback board working properly and temp sensors reading correct.

Thanks again Evan for the help

Kirk

MicroSquirt.com read only forum (Jan.15,2018)

Need 70% PWM to run w/ flyback board

Need 70% PWM to run w/ flyback board

update

FR302-DICT substitute

Update