Author Topic: High rev and load knocking and backfiring di after rebuild.  (Read 2386 times)

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Brotangp104lyf

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High rev and load knocking and backfiring di after rebuild.
« on: 07 March, 2017, 10:08:12 AM »
Just rebuilt my di after 600k in 16 years of daily driving. Runs fine when cold and not pushing it but as soon as she's warm and I start opening it up under and load it surges   blurps, start popping and backfiring then pulls hard then starts sputtering towards 6k until fuel cut at 6400. I get a 55 code but the di doesn't have a knock sensor to throw a code from and advancing my timing to around 17-18 degrees has helped as before @15 degrees was starting to pop around 3.5k. I've, shaved head, put de high port non roller cams in my roller head, used flat top pistons, removed intake baffles, removed cat and rear muffler, replaced all seals, gaskets, bearings etc and removed a/c etc, etc. My guess is I'm getting more air/fuel in, and compressing it more, I'm running 91 and now with mods should run 95+ and keep timing up towards 18-19 degrees. Without a knock sensor how does the di engine detect knock? I still have half a tank of 91 but am going to drain it and re fill with 98 and pray I'm good to go. Any help or advice would be appreciated as long as its not " chuck a 20 in there". Advice Lol, i know everybody hates the di like its some kind of child rapist but I've thrashed the pants off mine for 16 years and I'm yet to find a fault. Also  I plan to take this car all the way back around to 000,000 and keep the di so I'd like to figure this thing out. Tia


91 p10 x3
P11 x2
Aviner turbo x1
Wrecked n14x1
Fastest di engined Nissan ever 😊

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #1 on: 07 March, 2017, 08:47:35 PM »
I suspect all the changes you've made have changed the airflow characteristics of the engine to the point where the air/fuel mixtures are now lean enough to cause missing and backfiring. The best thing to do is to get a wideband sensor on the exhaust and find out what the mixtures are like.

Also bear in mind that shaving the head causes the cam timing to be retarded, which won't be helping the situation.
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Brotangp104lyf

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #2 on: 07 March, 2017, 10:10:50 PM »
Just had a look at what your talking about. Looks like that'd be a good place to start for sure. Will the standard ecu and loom accommodate one? I saw a kit by jaycar that goes with them, will I need that to or is it possible to splice it into existing loom? If I have to run an aftermarket ecu that's going to take a lil saving up Lol. It pulls much better down low but as soon as revs get up she's a mess. Kind of gutted after all the money time and effort and to have it  almost running rights just gutting
91 p10 x3
P11 x2
Aviner turbo x1
Wrecked n14x1
Fastest di engined Nissan ever 😊

Brotangp104lyf

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #3 on: 08 March, 2017, 09:21:55 AM »
Done a little digging and from what I gather to run a wideband sensor I need an aftermarket ecu. Haha catch 22 is try find one that suits a di off the shelf???? So I'm assuming I'll need some type/ brand of ecu and I'm stumped on which is suitable for a di. Any ideas under $1500?
91 p10 x3
P11 x2
Aviner turbo x1
Wrecked n14x1
Fastest di engined Nissan ever 😊

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #4 on: 08 March, 2017, 10:14:23 PM »
You don't need a wideband to be wired into the exhaust, units like the Innovate LM2 have a hand-held controller / display which will tell you what the mixtures are like. These Innovate units are what the club tuners up here in the Jafa box use to measure mixtures.
Kieran: thank you for being amazing... Have my babies.

Brotangp104lyf

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #5 on: 09 March, 2017, 11:40:33 AM »
Cheers they appear to only run on obd2 cars and I'm of the understanding mine is obd1 being 91 p10? I'm just learning aboutvthe ecu/ tuning side as all my experience is on the mechanical side. For the cost of a unit like the one mentioned would I be better off to throw a few hundred more on the stack and go for a stand alone? Pros vs con's? I am getting some 98 brought out and will play with timing again. If that doesn't work I'll try a colder plug. Failing that I'll have no choice but to get in there and go at it. Quick browse has pointed me at the link atom unit. I don't mind spending money for results as it's my daily ( well not right now) but I may look at doing more engine work later on why something that works with what I've got now but could be expanded on later. Cheers for the help, I'm a bit overwhelmed by the ecu/ sensor options. Around $1500 is where I need to draw the line or I'm in trouble. Lmao.
91 p10 x3
P11 x2
Aviner turbo x1
Wrecked n14x1
Fastest di engined Nissan ever 😊

Brotangp104lyf

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #6 on: 09 March, 2017, 02:26:49 PM »
A lot of bad reviews and complaints about that company and unit. For the money I'm not sure if that's the way to go considering its limitations compared to a more complete engine management system. I've looked at the link range because the old mans mates ran them on the race cars, them and motec so I know they're a pretty decent brand. I'm going to head in and talk to wrc developments here in hawkes bay and see what they recommend. On another note regarding the cam timing, what's a good medium between price and quality for adjustable gears?
91 p10 x3
P11 x2
Aviner turbo x1
Wrecked n14x1
Fastest di engined Nissan ever 😊

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #7 on: 09 March, 2017, 11:11:47 PM »
My guess is I'm getting more air/fuel in, and compressing it more, I'm running 91 and now with mods should run 95+ and keep timing up towards 18-19 degrees.

If you're running too lean then advancing the timing would only make the problem worse.

Done a little digging and from what I gather to run a wideband sensor I need an aftermarket ecu. Haha catch 22 is try find one that suits a di off the shelf???? So I'm assuming I'll need some type/ brand of ecu and I'm stumped on which is suitable for a di. Any ideas under $1500?

No. A "wideband" is a stand-alone combination of a wideband oxygen sensor, wideband controller, and AFR gauge. The sensor measures the exhaust gas and the result is displayed on the gauge. All you gotta do is weld a bung into the exhaust pipe, above 3pm or 9pm on the pipe (pointing downwards, NOT upwards) and at about a meter or so back from the exhaust headers/downpipe/collector. One like this: http://www.nzperformance.co.nz/innovate-motorsports-wideband-o2/oxygen-sensor-bung-plug.html

In fact, most wideband kits include the bung. This is the one I have: http://www.innovatemotorsports.com/products/MTXL.php

If you've changed cams, pistons, intake, etc. the tune will definitely be a bit off. Link Atom is a great choice, I've got the Storm Blue (the next step up) but my car is turbo and I wanted a couple more inputs. A cheaper option would be just a regular daughterboard and tune.

I wouldn't bother with cam gears on a mostly stock DI. Focus on the ECU & tune first, then add cam gears if you have major problems with overlap, idle, etc.

Quote from: Cameron
Darryl, what would it take to RWD SR convert my QG18 bluebird? Ive got a mate with a angle grinder and stick welder, surely it cant be too hard

Brotangp104lyf

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #8 on: 10 March, 2017, 04:01:43 AM »
Great info. Yeah I didn't want a tarmac eater and never expected it to be. Basically I've driven it into the ground for 16 years and thought "while I'm at it i might as well". I'll save a few pennies and get the link setup. I emailed the guys that do the addon boards but they can't do one for a di. Actually nobody seems to make anything for a di and theres virtually no info anywhere on them which makes things a tad trickier with no other knowledge base to draw from. Much appreciated info here. In regards to timing, I'm warming up, disconnect tps, rev a few times, setup light and putting pin at around 3rd or 4th mark on pully. This is how I'm setting timing up. Sound right?
91 p10 x3
P11 x2
Aviner turbo x1
Wrecked n14x1
Fastest di engined Nissan ever 😊

Brotangp104lyf

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #9 on: 10 March, 2017, 04:37:15 AM »
When I put the cams from the de in it was because the de intake cam appeared to have a much larger lobe and held valve open longer. Found 1 article that said it couldn't be done or wasn't advisable but I could see no issue. But.... I did also notice the rocker arms had much different profiles between roller and non roller arms.  Still everything opened and shut as usual and apart from depressing spring harder it all seemed OK. Now I'm wondering if it may be playing a role in whats happening. The cam gears I thought might be a good cheap upgrade to get a lil more out of it after the link is installed but yeah I'm much more worried about detonation than the cam timing at the mo. You'll laugh at my misfortune, haha. Just replaced rotors, pads, sway bar links and bushes, 2 engine mounts, and windscreen for WOF. At same time thought id give her a bday so did all my filters, new plugs, coolant, oil, etc. A week later the carbon tip went kabluey in the cap and had to limp and jerk the last 20km home using a piece of tin foil as a the carbon. Took 5 goes but got her home. $ 170 odd notes for the dam cap. ( 2 types 1 is like 30 bucks odd, of course mines not that one. ) new rotor for the f of it. 3 days later ring on no1 broke and smoke like ya wouldn't believe. Now I'm here with a rebuilt engine that revs to 4k and then runs like its on anti lag. Cars......
91 p10 x3
P11 x2
Aviner turbo x1
Wrecked n14x1
Fastest di engined Nissan ever 😊

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #10 on: 14 March, 2017, 11:03:03 PM »
Might also be in limp mode if it sounds like antilag. Which usually points to MAF problems.

One thing also is that the DI might have softer cam springs. which means more cam lift might be bad.

Sounds like it's just running shit because the combination of different pistons, cams, compression (shaved head), advanced timing, exhaust, intake baffles, etc. all adding up to making it run rough. In which case you need a proper tune anyway, so you may as well splash out and chuck the Link G4+ Atom in it :) For the versatility and extreme ease of use, the Link will hands-down "out value" any other solution.

I'm warming up, disconnect tps, rev a few times, setup light and putting pin at around 3rd or 4th mark on pully. This is how I'm setting timing up. Sound right?

In theory yes, but I hat that hocus pocus black magic. I just use the proper Consult connector and software (you have to buy most software actually; I bought NissanDataScan for about $55).

Quote from: Cameron
Darryl, what would it take to RWD SR convert my QG18 bluebird? Ive got a mate with a angle grinder and stick welder, surely it cant be too hard

Brotangp104lyf

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #11 on: 15 March, 2017, 10:37:19 AM »
Sounds about right to me and good to know I'm kinda heading down the right track. I've read the di maf is sold as the whole injector/ throttle body housing unit. ( best description I can come up with) I doubt I'll find a new one as Nissan don't seem to be good for much on p10s. I'm of the understanding that by going to the link unit these and other sensors can be swapped out with ease and new parameters dialed in. I've got it running on 98 now and its a bit better, can drive " normally" and even the first few high rpm runs it goes well to around 6k. After a few gear holds to there on a hill etc " get her hot" the effect comes back. On the springs I did do a lil research on the swap and it had been done before with no issues bar one thing I saw about possibly effecting the harmonics. I turned everything over by hand and then on starter to just watch it all and had a fraction more squash but still far off over doing the spring. The de lobes are by eye a mm higher and a tad rounder with a slightly different duration but compared to di almost the same. The di has no knock sensor so it just goes and goes without backing anything off till boom id imagine. I was reading about cleaning maf sensors but the di setups a tad different to the ones described. Got a way to go on the link but yeah I've done a lot of searching and for what it does for the cost and what I need it's a no brainer really, gotta get it. If you know any sites that deal in parts for the di I'm all ears to coz I can't find nutta on them. Kinda keen to keep playing around now just to be different. Down low it's way better than ever before, before I always had to rev to get it spinning but na she hooks 2nd easy as keeping under 5k. Thanks for the help coz I'm doing it all lone ranger myself.
91 p10 x3
P11 x2
Aviner turbo x1
Wrecked n14x1
Fastest di engined Nissan ever 😊

gbwelly

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #12 on: 15 March, 2017, 08:22:19 PM »
In theory yes, but I hat that hocus pocus black magic. I just use the proper Consult connector and software (you have to buy most software actually; I bought NissanDataScan for about $55).

Do you run this with Win 10 x64? Happy to pay for software as long as it will work.

Brotangp104lyf

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Re: High rev and load knocking and backfiring di after rebuild.
« Reply #13 on: 19 March, 2017, 01:39:36 PM »
OK well, with 98, throwing the dam timing gun away and going by ear, I got her up around 5½ k, removed the air cleaner and dohhh all the way to 7½! Sweet, bit raspy and spluttery but much better. So I'm still going for the link atom for peace of mind and future proofing but can get back to driving her once I custom fab a new intake and filter arrangement. The standard air box just can't get enough thru it anymore. Di's have a big plastic cleaner directly on top of injection but only a tiny little hole into the filter. Even with the pad out its starving then pop the top and she's away! Though about the old school trick of drilling a few extra holes but they'll just suck up heat so welder, grinder, Giles and snips are coming out.
91 p10 x3
P11 x2
Aviner turbo x1
Wrecked n14x1
Fastest di engined Nissan ever 😊