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TPI = Mass Frusteration!

Russell

Russell

3/4 ton status
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Jun 23, 2000
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Argggh, not that I expect any of you guys to know anything about TPI, but I'm getting right frusterated with the piece of junk!

I don't get it, so many people bolt the intake on, hook the wires up, set minimum air, and drive! Then there is me, I sit there for MONTHS trying to get the stupid thing to run right, without any progress at all!

I think I've replaced pretty much everything there is to replace on that TPI. I've replaced the injectors, all the modules, the ECM, the Chip, all the sensors, and it still won't work!

The thing idles at like 1200 rpm, if you go any less it stumbles and missfires something terrible, and it won't rev up at all. Open the throttle blades and it just backfires through the throttle body.

Sigh, I'm almost to the point of tearing all that stuff off, getting a q-jet, and actually make some progress on that stupid truck. Obviously I'm not meant to run any sort of fuel injection!

All it has for an engine is a 350 bored .020 over, with flat tops, and an XE262 camshaft. Other than that, its all stock. The TPI has basically all new electronics all the way around, the ignition system is all new. I just cannot figure out why this thing won't run!

I've attached a log of the truck's attempting to run according to the ECM, and here is a link to a video of the truck attempting to run:

http://media.putfile.com/MOV0007990
 

Attachments

  • 19800104_000012_LOG.txt
    2.1 KB · Views: 40
There are only 3 samples, but why is rpm 0? Not sure what valid values are for IAC, Temp, Map and so on, but it certainly should be showing rpm I would think. I'm sure that has not escaped your notice, so I guess there must be a reason for it that I don't see...
 
Sorry, I posted the wrong one, here is the right log:
 

Attachments

  • 19800104_000055_LOG.zip
    51.7 KB · Views: 35
are you sure your distributor isn't 180 out?

Nothing wrong with getting a log of readings at 0RPM. Just cause the engine isn't running doesn't mean the PCM isn't doing its job.

What program do I need to use to view this log file? I just have notepad at the moment(need to install word since I have it and all) but can't make sense of the stuff in notepad.

Anyone tell me what these values in the log file mean? I mean "TPS:22" means nothing to me...

I did notice one thing, it says "TCC Locked".... thats not quite right.
 
Well, at least that makes more sense compared to what I've seen on TBI. Was that sitting in place or moving? I expected speed of zero. Some of the numbers are moving around more than I would expect, but I know nothing of TPI, so I'm sure one of the EFI guys here will be able to point you in the right direction. Sorry I'm not more help (other than getting the right file up sooner than later). :)

Edit: Best bet, though it won't do you much good it seems, is to open it in Excel to get the columns lined up. And if 180 out, it shouldn't run at all.
 
Two guys that know their TPI stuff are Dyeager535 or HarryH3.

I'm pretty certain Harry did the swap when it was unheard of to do so. I'm sure either of these guys could help you out. You'll have to hope Harry sees this thread (membership lapsed) or you could pm Dorian...

Is that cam compatible with the TPI?

Rene
 
Hey dude. sorry to hear yer troubles.
Are you Speed density or mass air flow?
What wiring harness did you go with? I see you have a cam, who burned you a chip to match your setup?
What are your cam specs? Duration @ .050 and LSA?
What is your base timing at? Did you set the timing by unplugging the EST connector, set timing, then turn off the engine, hook back up the EST and fire her back up again? Check timing with it unplugged, should be something like 0-6 degrees, then with it plugged back in the timing should advance quite a bit more maybe 10 or more degrees.
What is your fuel pressure at? have you hooked up a gauge and see what happens at idle then when you romp on it? When i've had issues with my tpi in the past, i've hooked up the fuel psi gauge and duct taped it to the windshield so i can see it while i take it for a test drive.
Is your gas tank full? My setup surges for gas below 1/2 tank. I had some driveability problems when i first got the tpi running, finally figured it out when i filled up the tank!
Did you set the tps at ~ .54 volts when the throttle is closed?
Have you jumpered the A to B terminal on your ALDL and see if you have any trouble codes?
Is it going into closed loop after a couple minutes of warm up?
Did you do anything else to the motor, or did you just remove the carb and install tpi? didn't adjust the valves did you?

Too bad you aren't closer, i'd come over and take a look at it. ;)
 
my culprit for this kind of behavior in the past has turned out to be bad IAC's (twice). Although you did say you have replaced everything, so I'm not sure. You may want to check out www.thirdgen.org and goto the TPI and gen tech boards, there is info on there like no other on tpi swaps and people are usually very knowledgable.
 
Ok, a bit more information here, now that I am a bit more sane minded, and more determined than ever to get this thing running!

I'm running a mass air flow system. I've got an XE262 camshaft, I'll get the specs for it in a minute, but it isn't an overly wild cam by any means. Mild idle, makes power from 1200 - 5000 rpm. I've got the base timing set at 4 degrees, to get the computer to run a bit more timing. Plugging the EST connector back in does NOT change where the timing is. The tank is about 1/4 full, and I am not 100% sure where my fuel pressure is at. The truck is sitting still during this test, on flat ground. The reason why it is reporting the VSS moving, is that I put my tranny into forward and reverse to make it flow the juice around a bit so I could make sure the fluid level is ok. However, having no driveshafts, I was not able to put it back into park cause the output knuckle was still turning, hense the speed readings. The TPS is set at .53 volts at an idle, and I am recieving two trouble codes -- A rich flag, and a EST flag. The truck seems to go into and out of closed loop occasionally, so I will put a heated o2 sensor in. I adjusted the valves when I re-installed the heads by rotating the crank 90 degrees, and adjusting thes valves in the order that the cylinders fire.

IAC is one of the few electrical components that I have not changed, however, that will change pretty quickly here, as I'll order one up when I am at Napa tommorow to get a fuel pressure gauge / materials needed to hook one up.

Only thing I can see is that my 02 readings fluctuate a bunch, and that my BLMs are excessively rich at an "idle"

If anyone wants a slightly better organized excel spreadsheet of the information, let me know, and I'll email it to you. Its too big to upload onto the forum.

Really, only TPI savy people will know what the info means. A lot of it is still greek to me, not knowing where my IAC numbers should be etc.
 
Ok, cam specs are in:

Gross valve lift = .462 intake, and .469 exhaust.
Duration at .006 tappet lift = 262 intake, and 270 exhaust.

Valve timing at .006:

intake = 25 open and 57 close
exhaust = 69 open and 21 close

Specs for cam installed at 106 intake CL

Duration at .05:

intake = 218, exhaust = 224

Lobe lift:

intake = 0.308, exhaust = .313

LSA = 110 degrees
 
Something is WAY out of whack with your timing. :eek1: That is most likely what is causing the backfire through the throttle body. The EST error code is also pointing to something in the ignition timing system that isn't working. Are you using the correct distributor? You have to use the one that has no mechanical or vacuum advance so that the ECM can do its thing.

Try this: Retard the timing about 20 degrees from where it is now and then start the engine. I'm guessing that the backfiring will be gone... If it is, then we can troubleshoot from there. :cool1:
 
I didn't see mention of the distributor on your replaced list. The ECM gets its ignition firing signal(for timing) from the Distributor. Massively important.


O2 should fluctuate, if its not, something isn't right.
 
Distruibuter is the stock TPI big cap HEI. Has a new cap and coil. The dizzy internals haven't been touched at all, so there is that possiblity that the module, pickup, or something may be messed up. The dizzy does not have any mechanical, or vaccum advance devices on it.

I'd agree when you say that my issue is mostly timing. I went outside, and fiddled with the timing a bunch to see if I could find a position that it ran better at. First I did so with the over-ride plugged in, and as expected, didn't really see any difference at any dizzy position, then goofed with it with the over-ride unplugged. I got it to run pretty decently, although with some very high RPMS (2500 rpm or so) if I turned the dizzy a bunch counter-clockwise. I have terrible throttle response at any timing position. When I open it to WOT, I loose almost all vaccum, then it stumbles a bunch, and pops out the intake, and doesn't recover unless I close the throttle blades back up.
 
SierraClassic said:
First I did so with the over-ride plugged in, and as expected, didn't really see any difference at any dizzy position, then goofed with it with the over-ride unplugged.
Click to expand...
You should see the change regardless. The distributor has NO reference to TDC on these engines. It bases its timing curve on the assumption that the base timing is set correctly. It doesn't know how to adjust the timing to a particular number of degrees from TDC. It just advances or retards the timing a certain number of degrees based on a value it looks up in a table. If the current value is supposed to be +16 degrees, it will just add 16 degrees. It won't know if you have already advanced the base timing by 2 or 20 degrees.
 
Here's an idea... With the ESC bypass wire connected, see if the timing mark moves when you rev up the engine. It should move several degrees as soon as you open the throttle. If it doesn't, then we have to figure out why that isn't working. If the timing doesn't change with different loads then the engine is gonna run like crap.
 
Nah, its an 80 K25, and I've got a lot of money / effort into the TPI. I'll make it work yet :P

Its dark out now, but I am seriously thinking that timing is my problem now. I'm gonna do another vac leak test (take my propane torch, put a tiny amount of propane on, and put it by all of the connections, if there is a vac leak, it'll suck the propane up, and significantly increase my RPMs. After that, I'll check my fuel pressure. The injectors are new 22lb/hr injectors, that bench tested to be within 2% of eachother as far as flow rate goes, so only the fuel pressure could be the problem. If fuel is good, then that narrows it down to ignition, and having new AC Delco plugs gapped at .045, with new plug wires, cap and coil, that leaves only three things to be wrong inside, module, pickup coil, or the electrical advance unit.

I swear, I'll get this system running, if its the last thing I do!
 
If the pickup coil was bad then you would have no spark (and no fuel, since the ECM pulses the injectors only when it gets reference pulses from the ignition). So we just narrowed it down from 3 to 2. :wink1:

What number is the EST code that you're getting?
 
Ok, so lets focus on the electrical advance, since that'd appear to be the only thing that'd really be wrong here as far as timing goes (since the dizzy wouldn't pulse if it wasn't getting a good signal from the pickup coil)

How exactly does it work? Is there some sort of a little servo in there that moves the linkage arm around? How would a guy best go about testing it to make sure that it is working correctly?
 
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