Cornhusker

I finally received my new Prom from Jim at TPIS for my 89 vette manual trans with a mild cam from TPIS installed. After installed & setting timing at 6 degree I have lost the power she once had. I can’t even spin the 20 year old tires! I’ve called TPIS all day yesterday and no one answered. I could really use some direction here.

Kevova

There not alot to do but wait, you could use data logger and record several data streams to share. WOT, cruise, and idle. Tune by mail is not an exact science. There canbe some trial and error getting tune correct for your particular car. Every vehicle is a little different so tweaking isn't uncommon.

Cornhusker

I understand tuning to get max performance does take tweaking but to lose power, that doesn’t make sense to me. I’ve never heard of this before but my frustration is compounded by 1) an extra 2 week delay in the order, 2) they didn’t send all the items I ordered & 3) not be able to reach anyone at TPIS when a problem arises.

bjankuski

Down on power from what baseline? Stock prom?

THE 383 admiral

That is. The exact reason. Most DIY.
Nobody is going to put in the same level, dedication, time, trials, perfection as yourself.

VikingTrad3r

id probably install one of those horsepower apps on my phone, go do say 5 runs to get a baseline. Then swap the oem chip back in and do the same test.

It really doesnt matter if the horsepower app is super accurate or not. It gives you a baseline to verify your butt meter.

vader86

Nothing you can do with it but wait, tuning by mail is not exact, you will often have to send back and forth a couple times to get everything right, especially part-throttle driving.

If I were you, I'd hook up the laptop and datalog it, send him that log. He's not doing anything but messing with fuel/timing tables otherwise.

Cornhusker

Thanks for everyone’s input, it’s really helpful. Jim couldn’t find my phone number to call me back but thankfully emailed me this morning & then I was able to have him call me when he was available.

The only thing he could think of was to check timing & make sure it didn’t move off of 6 degrees advanced. I liked your guy’s suggestion on getting some baselines on how it runs then swap back to factory only chip & see what I can find. I don’t have the ability or knowledge on how to datalog but an old retired mechanic friend has a scanner & I’ll have to get him to hook it up to see if anything else maybe causing issues all of a sudden.

I had been running the stock prom with 8.5 degrees advanced but I’m going to wait on changing that, I don’t want too many variables in play.

vader86

Should be pretty simple. Get a laptop, get a USB to OBD1 cable, and download DataMaster or TunerPro RT.

Start the car with everything connected up, double click the DM or TP program icon and see if it talks, sometimes it can be tricky to get it to talk. Then you'll see the data on the screen, don't be surprised if your digidash displays nonsense while logging. I used DataMaster I think, and it recorded the data to a log file if you click a button, then email that to the tuner. You'll see things like the advance and knock counts, rpm, fuel trims, IAC counts, etc. Might not make full sense on the screen but its there.

When you log, drive the normal routes you drive to work or wherever, the part throttle tuning takes some work. Note the times yourself when you're just cruising along and expect more power or less. Take a couple rolling starts on an empty road and note that too. That stuff makes a lot of difference. I had to tell my tuner to sit in the passenger seat and ride with me to get mine right, and some days I still don't think its quite right. Mine was tuned in May and if I drive it in winter it sometimes doesnt want to idle.

tequilaboy

Ask for a copy of the bin file, a change log, or a text export to see what exactly has been changed.

Here's a text export of APYP for example.

THE 383 admiral

Good example of sound advise.
Many "tuners" simply touch WOT only.
A few deg of timing. Call it a day.
That is NOT a tune.
The factory cookie cutter baseline from any of the "Manufacturers". Is a joke. way to rich.
Unbalanced DFCO
Especially 80's - 91 (92 up).. manufacturers started to slightly improve.
That is why a real tune easily nets 40hp.
Most owners bolt- on, build. Do not have anything to monitor. Now you can use your phone.
So. They mail out a PROM. And expect perfection.
And have no way to validate changes.
Simple example. Hypertech way back.. owners vested in equip to validate. To learn. Only slight timing.
adjustments. For hundreds$.

Myself, and others. experimented/ disected every table. DM logged & dyno, wideband, track time, trap, results.
End results incredible. Including MPG, throttle response.

Cornhusker

I was looking for an Obd1 to usb & not finding anything?

That’s why I went with TPIS, I figured they’d been in the TPI cars the longest & would have it figured out, plus they’d know their cam that I installed.

Kevova

It would worthwhile to be sure balancer ring hasn't moved. Was engine " burning tires" with stock chip after cam was changed?

Cornhusker

Harmonic balancer is 4 months old

vader86

CABL1 OBD1-Style ALDL Connector [CABL1] - $30.00 : Moates.Net

Cornhusker

I double checked the base timing & it’s at 6 degrees. Took it out for a couple runs with my phone app “GPS Race Timer” & was getting 8.4-8.6 second runs from 0-60mph. Driving it around it definitely doesn’t feel like it has the power it had before. I’m going to pull the prom then run 0-60 a few more times to see what I get.

A little background: after I finish putting the engine back together (around the start of July) after 7 months of repairs including the new cam 220/220 duration 456/456 lift & 112 lsa, it didn’t idle great & had hesitation & surging when just coasting in 1st at around 1000rpm. However when I hit the gas full throttle it pulled really hard! Eventually I diagnosed leaking fuel injectors, the Bosch 3’s (22lb) I had just installed. So instead of getting the bosch’s redone & having the same or other issues I bought a new set of Accel’s (24lb) injectors. Installed them but at 1st it felt like she didn’t have the pull she once did. I did an autocross event in the middle of September & actually noticed a little bit of surging as I idled to the start line.

So as I’ve been over this again & again & again in my mind I’m starting to wonder if the Accel 24 lb injectors helped drivability but indeed did kill power? Not that I want to take it apart for a 3 rd time but God I want it to just run right!

Honestly at this point it’s hard to remember if the power really did come back like I thought it had, or if I was just hoping & tired of working on it. So that brings things to today, I’m 99.9% sure she doesn’t pull like she once did but I’m also coming up on 12 months of trying to get this thing running right. Honestly I’m getting mentally exhausted with this dam car & still have the pressure leaking down within a minute after key on test. I’ve tried dozens of times to pinch off the lines & it doesn’t effect it at all. So I must have the wrong tool for that. I still have that to deal with & who knows if it’s effecting this problem or not. Jim at TPIS was supposed to send another fuel pressure regulator with the prom but he forgot to send it. He’s so bloody slow at sending things I told him yesterday to hold off on it for now.

Any thoughts, different direction one might suggest? Could I really be getting dramatic differences in power from the different injectors?

THE 383 admiral

To save yourself time an aggravation.
Purchase a fuel pressure gauge. It's a EFI invaluable tool.
**As long as you are positive your regulator diaphragm is not torn. Leaking.. and a constant 43 - 45lbs idle, driving, WOT
Do NOT stress about the bleed off time.
It's actually an aide for small pumps. To help start-up.

**The FP check valve is not actually required.
It does however change the way you start.

High performance pumps like my Aeromotive.
Do NOT have a check valve. I have had this combo for about a decade. Must start at prime. Will NOT start after prime. It's actually a great anti theft deterrent.