robp823 Posted February 4, 2010 Share Posted February 4, 2010 What method are you guys using to diag weak injectors.Have a 2001 f-250 here that runs a little rough at idle and coughs a bit through acceleration.My dealer has the injector performance analyzer.no codes.Has anyone had expirience using this??Any input or advice would be great.Thanks Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 5, 2010 Share Posted February 5, 2010 Look at Perdels in scan data, it's the forerunner of the 6.0 cylinder balance graph and will pick out weak cylinders very quickly. We've covered it before, scroll down this page: http://www.forddoctorsdts.com/forums/ubb...=true#Post22830 Keith has a diag video on the 7.3 I sent him tha covers scan data diagnostics live on a 7.3 with an NGS, perhaps we will put it up on the website soon. PS: Be forwarned: If you have some bad injectors, I suggest changing all 8. Commonly you'll find a couple weak, change them, and now you have a couple strong and 6 weak. BTDTGTTS. Also, beware of low compression on the holes in question, I suggest you check it physically. I'm helping a local shop do diag right now and we had 2 7.3's this week with a bad hole. One had a zillion parts thrown at it by another shop. Good Luck! Quote Link to comment Share on other sites More sharing options...
Mikill Posted February 5, 2010 Share Posted February 5, 2010 I too would suggest checking compression. Damn near every 7.3 that comes into the shop gets a compression check before I put an injector in. I have been bitten by that twice and learned to check compression first. Quote Link to comment Share on other sites More sharing options...
Alex Bruene Posted February 5, 2010 Share Posted February 5, 2010 I find my ears are very useful in audibly locating weak injectors. Quote Link to comment Share on other sites More sharing options...
robp823 Posted February 8, 2010 Author Share Posted February 8, 2010 Bruce, this may seem like a dumb question but If perdels can only be used on 99.5 and newer then what can we use on 94-97 model years??Also got a link to break down mfdes and its use for me??Keith where are you???Lets get this video up! hahahhah. Go 99 and 18! Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 8, 2010 Share Posted February 8, 2010 There's an injector cutout box that can be used on earlier models which opens the circuit to each injector while the motor is running. Comparing MFDES numbers while the injector circuit is open will tell you what's strong and what's weak- the ones that move the least are the weakest. Running the contribution test multiple times while the tranny is in gear will commonly flag a weak cylinder. For some reason, running the test multiple times tightens up the failure parameter. Using other methods like a IR gun to determine weak cylinders. Most Gen 1's up north are lucky to be running at all, much less running perfectly smoothly. As trucks get older, owners are less fussy about perfection. The PCM will flag a dead cylinder "relatively" well, Perdels aren't for flagging a dead hole, just a weak one. I'm in FL right now, and I've seen more mint PSD's than I have in a long time. I just drool at how nice things stay down here. Good Luck! Quote Link to comment Share on other sites More sharing options...
robp823 Posted February 8, 2010 Author Share Posted February 8, 2010 Its funny you say that Bruce.My dad has been living down there for quite sometime now and has been shopping for a new truck.Thats all he has been talking about is how clean some of the older trucks he has looked at are.He looked at some older models that look like they just rolled off the showroom floor.I told him next time im in the neighborhood for a truck im coming down there.Thanks again ,enjoy FL! Quote Link to comment Share on other sites More sharing options...
STROKER_T Posted May 20, 2010 Share Posted May 20, 2010 Bruce...thanks so much for the refresher...very cool I got an '01 here as well and tried the perdels method,as i've always relied on my ear as was mentioned...inj 2 is at 6%...4-6-8 at 2-4%...but as it warms up,#8 shows 4%...the others chill... So,I'm thinkin I got a 'stiction' concern....got all the signs includin 268,000 miles...customer swears he's got a glow plug problem,cause when he plugs it in the truck runs great,i explained to him about the injector stiction concern...not to mention it just left our top competitor after 2 months w/ same concern...now i got it...the customer is pissed and alot lighter in the wallet... p.s.- had no idea one can run a contribution test in gear on a 7.3..... Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted May 20, 2010 Share Posted May 20, 2010 You need 8 injectors, as they are all compromised. If you chase the high ones the comparitive lows will shift to other cylinders. Do your basics like fuel pressure and maybe a compression test, and probably suggest 8. Good Luck! Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted May 20, 2010 Share Posted May 20, 2010 ...and I will vouch for replace all 8 advice. Several times I have replaced a few injectors in an older 7.3L engine only to have to go back in and replace the rest. While the cost is higher the customer (and you) will be happy... the first time. Quote Link to comment Share on other sites More sharing options...
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