350dave

New to the forum, but far from new to cars (and Chevy 350s). I've owned 2 C4 Covettes and my latest project is an '89 Firebird Formula 350. I've read a ton about doing my own tuning, but so far have only conquered the basics (reading existing chips, writing those tunes to my own chips, and data logging). I'm using Tuner Pro R/T and the appropriate hardware from Moates.net.

The Firebird didn't run properly when I got it. It was in limp mode (a.k.a. "get me home" mode) and had both a MAF code and an O2 code. I assumed one or both needed to be replaced and I'd be on my way. That was 8 months ago and I've only managed to keep going backwards. When I got it the car had the Edelbrock Hi-Flow Intake Manifold and Runners, 36 lb/hr Accel Injectors, aftermarket cylinder heads (World 305 heads that I've since had the local machine shop make right for a 350), and was bored .030 over (but not stroked). It has an aftermarket camshaft, but not sure which one (although several measurements at the lifters when I had the heads off, with the correct tools for that job came out to a .490 - .510 lift... no clue about duration). It did have a Hypertech chip in it and I wrote Hypertech about it... all they could confirm is that it was indeed a custom tune and that they haven't done those in about 15 years... which lined up roughly with the timeline I was given on when the engine was rebuilt. So I can't say for certain that the Hypertech chip was actually designed for this mechanical setup, but there's a decent chance of it. Basically I bought someone else's project, and based on my past successes with resurrecting and restoring mechanical blunders that others have made, I naively thought I'd have this puppy roadworthy within the first month.

I know I have at least 2 issues... low engine vacuum and running extremely lean. In limp mode the car ran extremely rich, so at one point I downgraded to Accel 24 lb/hr injectors (those are still installed) with my theory being if I could get everything returned to somewhat close to factory I could at least get the car driving reliably on the factory tune. I also looked up the increased CFM I should expect from the Edelbrock and it's roughly an 8% increase, so I figured the injectors should be roughly an 8% increase as well (24 lb/hr vs. the factory 22 and change). I can only get data logging to work on the factory chip. It will not work on the Hypertech chip, nor will it work on a chip I burn myself with the goodies from Moates. I've attached both BIN files (text versions attached too) and also my log from the factory chip (the forum will only allow me to upload the CSV log export). I've done more parts chasing than I care to admit, so I'm specifically posting here because ideally computer diagnostics will lead me down the correct path.

Any guidance the group has regarding why I can't get data logging to work on anything besides the factory chip, and/or how to address the lean issue would be greatly appreciated. I've chased down all the vacuum leaks I can find and I still have low engine vacuum. If anyone has experience with bigger camshafts in these cars and the engine vacuum I should be able to get with that setup I'd greatly appreciate that as well. I may be chasing ghosts on the vacuum problem and just won't get more with a hopped up cam.

Thanks a bunch!

350dave

I know the thinking is to get everything mechanically sound first, then start tuning. Is that true for highly modified setups, or do you get to a point where you need make hardware tweaks and software changes in parallel?

For example, I've tried adjusting initial timing and idle slightly, but I don't see the vacuum increase as a result. My vacuum is really low... around 10 inches at idle. For those with experience with bigger camshafts, wouldn't I need to make software changes if I get more aggressive with adjusting idle and initial timing (e.g. tell the computer we're no longer at 6 degrees initial timing)?

It's also worth noting the car does still have a functional EGR. It had EGR on it when I got it. When I had the heads machined and a 3-way valve job done on 'em, I ordered new intake manifold gaskets for an EGR (only to find that the gaskets the previous owner had installed were the style that blocked off the crossover). Since I had already done other troubleshooting on the EGR I elected to install the gaskets I'd purchased (ones with an open crossover) when I reassembled everything. I've had a few suggestions to remove the EGR because that can cause vacuum problems... not sure if others with larger camshafts have any experience with both setups.

I've got full, consistent fuel pressure at the fuel rail... the injectors are effectively brand new... no other indicators that anything is wrong except for low engine vacuum and running extremely lean.

Any/all suggestions would be very welcome.

Thanks!

tequilaboy

Your log: https://datazap.me/u/tequilaboy/fire...&mark=1047-497

MAF, LV8 and injector pw are all very high for an idling engine (about double what would be expected). Engine is working hard to compensate for dead cylinders pumping air, hence the lean O2 readings. Tps voltage also high (0.69 volts) suggesting significant throttle opening just to run.

Be sure to open and save the Hypertech bin to at least update the checksum. After that you can correct the mask id from AA back to 6E and re-save again.

Not much of value in the Hypertech bin anyway. Fan on/off temps (for 160 ° stat) plus minor spark advance, idle rpm, tcc and PE changes only. Factory bin is APYU (based upon scan id 3531) and Hypertech is clearly based on the same bin.

350dave

Thanks so much for taking the time to go through my log and share your observations. I clearly still have a lot to learn!

The more I looked at the difference tool in Tuner Pro R/T I was leaning toward the same conclusion... not much value in the Hypertech bin anyway (although I did notice checksum was disabled). I guess that's the reason I can't data log (can't connect) against those files (trying to use a 6E.xdf on an AA BIN)?

Given the MAF, LV8 and Injector Power findings, should I keep working the low vacuum problem, or is moving to tuning open loop fueling (starting with the factory BIN) the best next step?

Thanks again!

tequilaboy

The low vacuum/elevated load is due to the high engine friction, presumably caused by one or more dead cylinders. Check the firing order, condition of plug wires and plugs along with the cap and rotor. Likely an ignition issue resulting in misfire.

Got any logs in closed loop? If not, it would be interesting, but I suspect the BLM will just climb to 160 adding fuel.

350dave

tequilaboy, I can't thank you enough. I think you're spot on, but will make some improvements this afternoon to test the theory. I've been testing compression without the ignition system enabled (the traditional way with a gauge), but I do have some suspect spark plug wires. The traditional test is showing full compression in all cylinders, so the ignition system could very well be the problem.

The car has headers so it's extremely difficult to keep the plug wires off the headers with the Delco plugs in. I'm going to go to a different plug (e.g. NGK) because they thread into the heads further and help keep the plug wires further away from the headers. I also have replacement plug wires already here because I knew a couple needed replacing.

Unfortunately I don't have other logs, but will log again once I complete the work on the ignition system.

Thanks again!

TTOP350

iTrader: (8)

I know .490 and 510 lift was used for a early SLP cam (I'm sure it could be any other as well).

As far as sparkplugs, make sure you don't use plugs with to long of threads. The factory heads don't have much thread in them. Stick with a stock plug if you have stock heads.

Any pictures of the engine compartment and car?

350dave

TTOP350 - yep, I thought of that after looking at a few different options. This afternoon I was able to put in Accel header plugs (gapped 'em properly first, of course) because they have about the same amount of threads as the Delcos, but end up being much shorter. I also got rid of my valve cover mounted plug wire spacers/holders because they were actually pushing the plug wires closer to the header.

I've attached an updated log file. This time I was able to drive the car (about a half mile, I think). It was running lean, but I was hoping to get to closed loop. For several months now I couldn't go more than an eighth of a mile without the check engine light coming on. This time it didn't come on at all until the car actually died on me.

I'll look through the log file myself after dinner, but wanted to get it posted a.s.a.p. in case others have further suggestions.

One suggestion I got in the TPI forum here was to make sure the temperature sensor that the computer monitors is good/calibrated. Apparently issues with the sensor (or the wiring in that circuit) is a known cause of running lean. In my car there appears to be two coolant temp sensors (one in each cylinder head) and the air temp sensor in the plenum. Does anyone know which one the computer monitors?

I have pic's of the engine bay, but I'm an Apple guy primarily so I'll have to convert 'em to JPG format. Will convert and upload when I get a chance tonight.

Thanks again!

TTOP350

iTrader: (8)

ECM coolant sensor is in the front of the intake.
2nd fan switch is in the pass head.
Driver side head is the dash gauge coolant sending unit.

tequilaboy

Not too much to go by with the latest log due to limited data, but the fuel trim behavior in closed loop does show a bit of a lean tendency with the BLM climbing to 139 in cell 5. Load is still elevated quite a bit from where it should be, so engine is still working hard to overcome frictional losses. O2 signal is also a bit erratic. I'll add more comments if I see something worth noting.

https://datazap.me/u/tequilaboy/fire...=1133-1292-984

Even during decel, load and injector pw are relatively high. Load under decel should be even less than idle load. Maf signal is responsive relative to tps, so no indication of a bad maf,

https://datazap.me/u/tequilaboy/fire...5-741-934-1167

At some point would be a good idea to adjust the tps for 0.54 volts at idle, but this is not your main problem at the moment.

350dave

Yep, I had the TPS calibrated, but then needed to remove the throttle body due to a leaking gasket. So TPS needs to be recalibrated.

Thanks again for looking through the logs and sharing your insights. I really appreciate it!

Here a couple of pic's:



In the 2nd pic... please tell me that the plug on the front of the intake manifold isn't where the ECM temp sensor is supposed to be... ?

If so, I don't even see any wiring there. When I look through my photos from the top-end rebuild (just after I put the heads and manifold back on, prior to adding the plenum) there's no other place I can see on the manifold for a temp sensor. It appears maybe whoever did the original rebuild 15'ish years ago just thought that temp sensor was optional?

Thanks again!

Tuned Performance

iTrader: (92)

Cts is next to that. That’s where the csi timer switch goes.

350dave

Next to that meaning closer to the driver side?

I’ll check again when I’m back home, but didn’t see anything.

Tuned Performance

iTrader: (92)

Yes under by coolant to throttle body hose.

Orr89RocZ

iTrader: (20)

The one in the pass side head is likely fan switch

350dave

I found the cts... right where it should be. Thanks everyone for the helpful tips.

I haven’t tested it yet to make sure it’s functioning properly, but odds are that’s not my problem.

The quest continues...

350dave

I replaced the CTS to be safe. I also found that the distributor cap wasn't fastened down to the distributor very well (stripped threads on distributor), but I've since addressed that as well... it's now nice and snug.

Attached is the latest log file (open loop only... just idling in the driveway) and it seems none of those changes had a meaningful effect.

Here's my latest theory... the high temp/friction condition is due to ignition timing being too far off. The initial 6 degrees, and likely everything about timing curves are totally non-optimal given I have an aftermarket, hopped up camshaft. Does that make sense? Go right to tuning?

Do I have what I need to do tuning in the car with Tuner Pro R/T, 27SF512 chips, the Moates.net G1 adapter, and an ALDL cable? Or do I need additional emulation hardware? I've read conflicting info on this.

Thanks again!

Orr89RocZ

iTrader: (20)

Need a burn2 programmer

350dave

I've got the Burn 2 as well and I've successfully programmed chips outside of the car (not installed in the G1). Is there a way to do this while everything just stays in the car?

Or do I use the Burn 2 on the bench to make a few preliminary changes (e.g. disable checksum, etc.) and then I tune while in the car? I assumed the point of using emulation was to tune while the car is actually running, right?

Sorry if I'm missing something obvious.

Thanks again!

Orr89RocZ

iTrader: (20)

Never used an emulator. I just do runs note things that need done, then pull over and review logs, make changes as needs and burn chip. Start again lol. Its a process. Tune on the fly is good for minor things like idle and possibly some cruise but hard to drive and make changes at the same time.

350dave

Got it, thanks! I guess since you can playback a log in Tuner Pro, the ability to do things on-the-fly is a “nice to have.” It’s not like I have a dyno so your point is a good one. I’ll quickly get to a point where I need to be logging while driving… can’t tune and drive at the same time!

tequilaboy

Latest log with new cts: https://datazap.me/u/tequilaboy/fire...1&mark=1038-44

New link to same log (first one doesn't open/display properly, retry): https://datazap.me/u/tequilaboy/fire...65&mark=983-51

Nothing remarkable other than tps still high at 0.67 volts and IAC dropping to zero at 800 rpm. Maf/load/bpw still high for idle conditions. I would suggest collecting more data in closed loop before changing anything other than the tps/min air adjustment.

What makes you think its running lean other than the target afr and/or O2 signal behavior? Due you have a WBO2 sensor? Maybe I missed something earlier.

350dave

Just going off the O2 sensor data for lean condition, but I was reflecting on your point regarding high temp/friction condition and looking for the mechanical explanation. I know it has a hopped up camshaft, but don’t know the exact spec’s (only have reliable measurements at lifters to confirm). Mechanically speaking, from what I’ve read, an aggressive camshaft requires significant changes to ignition timing. So, it seems logical to adjust timing and see if that improves the high temp/friction condition. Make sense?

350dave

Closing the loop on this. My main issue ending up being a bad pickup coil inside the distributor. I had done the ICM, plug wires, cap and rotor... everything but the distro. Once I dropped in a new Delphi distributor the car started running much better. The bad pickup created a misfire condition. I've spent a fair amount of time working out a few other issues (primarily exhaust problems, then realized I had to wire in a heated O2 sensor)... and now, with the help of Ryan at Sinister, it's got a custom tune and it's very happy!