bigorangejeep

I am a first time poster here on Third gen. I have been looking around here for a while and have decided to ask the people that seem to have the most experice with TPI's.

This is my problem: I had a brand new engine built by a local engine builder with the following specs: 383 Chevy stroker (all roller) , alum heads, 10:1 compression Comp cams XFI 268 cam, and a brand new First Fuel injection TPI. No expense was spared on the engine build and all top of the line componets where used. I run the 7730 computer and all emissions related items have been deleted from the chip. This engine was built for off road use only and now lives in a custom CJ-7 Jeep. The problem is that it has never been exactly right since day one! The engine would crank, and run on the original chip that was sent, but it was way rich. It would foul plugs and cut up and never run smoth. It would seem rich from idle to 2,000 rpm's and lean up on top. It did perform, but just seemed like we could get it a lot closer. After taking it back to the guy who built it 5 or 6 times I gave up on him. He is a great engine builder and a super guy, but I do not know if he was a good fuel injection tunner. So I contacted a professional TPI tuner and have been working with him for the last two months but still have not fixed this agravating engine.

After working with him he has taught me a lot, but even he seems stumped on this engine. After buning about 8 chips he has somewhat also given up on this project. This is what it is doing: It will crank and run with his new chips but it will not datalog consistant information. It goes from rich to lean very quickly and then just keeps getting more lean the longer it runs. The following items have been changed or replaced trying to fix this problem over the last few weeks.
1) This programer had me change the mcal because it was using what he
thought was a six cylnder mcal. I actually had a V8 mcal from a previous build and used it. ( I am using a Moates adapter with the v8
mcal and SST chip.)
2) The injectors (Bosh 24lb) were ultrasonicly cleaned and inspected by FIC in Atlanta (good people to deal with).
3) Fuel pump was replaced with a Walpro 255 liter per hour unit.
4) New Mallory 4305 adjustable fuel pressure regulator was installed.
5) Fuel filter between fuel pump and engine has been cleaned at least
15 times.

This engine has about 30-50 hours on it. That is it. But it still has not run correctly since day one. It has run for 3-4 hours a couple of times pretty good but then goes right back to cutting out, surgging, and just does not act like a new motor should.

Now the tunner thinks that maybe there is a ground issue in the wiring harnss somewhere and has suggested buying a whole new harness from Painless to replace the existing one. If I knew this would fix it, I would order it ASAP. I am just getting tired and broke from throwing money at this thing and nothing has seemed to work.

Sorry for such a long post, but just trying to give the "Cliff Notes" version of where I am at with this thing. Any help or suggestions would be greatly appreciated.

Thanks,
Mr. I wish I had never seen a TPI

sgt473

Do you have the ability to hook a scanner and obtain sensor readings? TPS, ECT, MAT, I'm sure that will aid in the diagnosis.

bigorangejeep

I can borrow one, but I have been using Datamaster on my lap top.

ploegi

Being able to monitor fuel pressure while it is misbehaving would be good as well. What size fuel lines ya got? Have they been closely inspected for kinks/collapsed?

Cleaning a fuel filter? Hhhhmmm.... they are cheap enough, buy a new one. (though I doubt this is the problem.)

You have probably already learned enough, that investing in prom burning equipment of your own would be a thought as well. The stuff is easy to come by, and not that expensive. (aside from perhaps the required laptop....)

bigorangejeep

Fuel pressure gauge is mounted on the regulator under the hood and rises as you crack the throtle but I can not see it going down the road. The fuel lines are -6 braided lines that should not kink and they are not very old so they should not collapse either. The fuel filter is a Russel screen type wash out style and yes I do have a Burn 1 from Moats and cable to burn my own software. Although I do not feel comfortable enough to make the changes by myself just yet. I have been letting the tunner email me the data and I have been burning the chip. Also the timing is set at 6* and the only code that I get is an occasial 44 (exhaust lean). I do not get this code every time, but once out of every three of four runs which last about 5 minutes or less.

ploegi

Do some data logging with the laptop. It should have that capacity. Monitor fuel/air ratio, TPS value, and the rest mentioned above. (I would also include knock sensor in there.....) Have a look at the data, and see if anything jumps out at you when the problem occurs. The data might point you in the right direction.

Temporarily plumbing your fuel gauge to someplace you can see it while driving, and just duct-taping it in place would look ugly, but, it would work. (I have done this on my bird before...... tells some interesting tales.)

vetteoz

iTrader: (13)

Datamaster beats a scanner anyday.Records every input to ECM
Do some logs then run the same question by the guru's over on
3rd Gen DIY-prom
https://www.thirdgen.org/forums/diy-prom/?daysprune=-1
Ask someone to have a look at the logs for their thoughts
Is it going into closed loop?

It will not datalog correctly or the info it is datalogging is
in consistant?

irocuroc

just by chance. What knock sensor are you using. Was it off a donor car? It must be a 350 sensor with a 350 computer. The knock sensor can pull 20 degrees of timing out for no reason. Sounds like you got something other than TPI problems. Was the cam degreed properly? Tpi systems are easy, simple systems.. I think since it has never ran right that you check the hardware next.

bigorangejeep

I have plenty of logs on file for someone else to look at that understands them better than I do. It data logs fine, but it just goes from rich to lean then back to rich then to real lean.

As for the knock sensor, it has never had one. Again this is a new harness from FIRST and the it did not come with one, so the chips have the knock sensor eliminated.

As for the cam, it was installed by the machine shop that built the motor so I think it is good. As a matter of fact this motor dynoed some very strong numbers on their engine dyno. (428hp and 510ftlb of tp) But evey since it has been sitting in the Jeep it has been hit and miss on how it would perform.

Does anybody think it could be a bad ECM?? I am just wondering, it is a lot easier to change than the entire wiring harness.

Any and all suggestions from someone who can help will be greatly appreciated!

ploegi

switching from rich to lean is pretty normal. If it is staying to either side for any appreciable length of time, then there is an issue.

Bad ECM? possibly. They are basically a dime a dozen from the scrapyard, couldn't hurt to try another one, although, trying to fix it by throwing parts at is (as you have noticed) can get rather expensive.

I am not an advocate of replacing the wiring harness unless/until it is proven faulty, at which point, isn't there some kind of warranty?

Post some logs in the DIY Prom forum, let them have a look. A very good idea.

bigorangejeep

I will post them and see what type of response I get.

As for the wiring harness, my gut says this is not the problem, and that it is in the istallation or falty chassis ground, bad relay or something of the sort. I have not even asked about warranty. I have a friend that has a spare ECM, I think I will borrow it also.

88gta_hiflyer

iTrader: (1)

Sounds like either a sensor or your ECM. The sensors that determine your air fuel mix are as follows:
Mass air flow or speed density (depending which setup you have)
tps
oxygen sesor

I would try all of these before replacing the ecm but if you do replace the ecm make sure you get the right one. They are model specific but since your engine is custom it's hard to say which one you need. Hope this helps.

bigorangejeep

This is a speed density system. As for the sensors, the O2 sensor was a single wire unit that I replaced with a Bosh three wire heated unit. It is about a month old. The map sensor and the tps are the original sensors. The ECM is the 1227730. I do not know if that is the correct one, but it is the one that they sent.

If the sensor was bad wouldn't have a code?

ploegi

Not necessarily..... your best bet is still going to be having a look at the data, (or, having someone else have a look at the data) and see what is going on there.