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  #16 (permalink)  
Old 03-14-2013, 07:41 AM
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The 1994-95 systems run at a higher fuel pressure thanteh 13 psi the 88-93 systems run at.

peace
Hog

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  #17 (permalink)  
Old 03-14-2013, 07:23 PM
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This engine is an 89 so the fuel pressure, according to the books, should be 9-13 PSI thanks.
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Old 03-15-2013, 01:02 PM
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You need the correct PROM and calpac. This is what tells the injectors how long to stay open, based on various sensor readings. If the PROM is for, say, a 350 not a 4.3, you will be driving the injectors to stay open waaay longer than needed for a 4.3. Get the right programming in there. You may need to have a custom PROM burned if you have deviated much from the stock internals, but get one that is for your application, and I bet many issues are solved.
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Old 03-15-2013, 05:23 PM
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Originally Posted by sbchevfreak View Post
You need the correct PROM and calpac. This is what tells the injectors how long to stay open, based on various sensor readings. If the PROM is for, say, a 350 not a 4.3, you will be driving the injectors to stay open waaay longer than needed for a 4.3. Get the right programming in there. You may need to have a custom PROM burned if you have deviated much from the stock internals, but get one that is for your application, and I bet many issues are solved.
I had been hesitant to do that because the technical support guy from Painless Performance said that even though I had a different cal pac and prom from what Painless specified,the engine probably run OK, initially making me think my problems were elsewhere.

Looking back on that statement, it's a really dumb thing to say since he had no idea what I had in there for chips so predicting anything was a total shot in the dark.

The engine is bone stock with the exception of a full dual exhaust system. Painless does specify an ECM part number, a PROM part number and a Cal-pack part number. The correct parts have already been ordered (AC Delco parts). Now my thinking is that it's dumb to think the engine will run like it should when I'm not using the parts they said to use.

Today I took delivery of a 0-30 PSI gauge to more accurately measure my fuel pressure. Right now I'm reading 11-12 PSI on a 0-100 PSI gauge, which may be slightly inaccurate.

It's a little discouraging that the three technical support guys I have engaged in this project Holley (fuel pump) Painless (FI harness) and Dolphin (gas gauge) have all given me information that's kinda bogus and has caused me to waste time (and some cash) in the process of getting this truck finished. I am far from a know-it-all but everything I have done on this truck, and I've done EVERYTHING but the final basecoat/clearcoat and the seat upholstery, has come out beautifully I am totally pleased with the results.

The difference here between what I have done and what I'm having trouble with is that I fully understand everything I have done. The other examples I cited involve my reliance on "tech support" guys for stuff I'm not clear on. Once I get by each little hurdle, the bulb goes on and I'm that much more well educated for it. But the assumption I had made is that these guys should be more well educated than me.
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Old 03-16-2013, 05:06 PM
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Does it hold fuel pressure for a while after you shut it off. If not the regulator is suspect.
Any chance of you getting hold of a '89 ECM for a little comparison? I figure you already thought of that. Might be the quickest diagnostic test you can perform. Maybe even cheaper than you might imagine. I would think you could talk a local salvage yard into letting you borrow one for a little cash deposit/small fee. Worth a try. It sure could narrow things down.
If you get similar symptoms, look elsewhere(wiring harness for instance).
ssmonty
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Old 03-16-2013, 05:44 PM
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Codes can be set for many componenets without going into closed loop
TPS, MAP,CTS and some others will set codes without going to closed loop, under circuit failure conditions, like an open circuit or hard short.
Good move on the 0-30 PSI gauge. I have a 0-15 PSI gauge to test TB systems with as one or two pounds can make a difference. A 0-100 PSI gauge is as accurate as using a shotgun to kill a mouse, it works, but not as well as a piece of cheese and a trap.
Verify your fuel pressure is correct, then veriy you have the correct injectors and Throttle body. If you are sure they are both correct, then check live Data and look at the coolant temp value. It can read -40 and set a code ...or not. Either way it will run real rich.
Be sure your MAP sensor has a solid manifold source of vacuum, also check it on the data stream, manipulate the sensor and watch the reading by unplugging the vacuum and see if the value changes.
Lastly...as I said before you cannot setup the Minimum air rate with it running so crappy, and setting the TPS is part of the procedure. So adjusting it the way you did is futile.
Also you should be able to turn on the key, unplug the TPS, MAP sensor, Coolant Temp Sensor and then....leaving key on, after plugging the components back in, jump the ALDL and it should spit out codes for those components. If not....Then the ECM has problems that may also stem into the base operational systems as well.
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  #22 (permalink)  
Old 03-16-2013, 09:54 PM
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Thanks for the additional information guys. To provide a little more data...
The ECM in the truck using came from an 89 4.3 Astro van, although there is a notation on the service tag that is simply "88" written in ballpoint pen. It currently does not have the the Painless specified PROM or Cal-pack. The correct parts are in transit now.

There's not much of a chance of finding an ECM for testing purposes around here as the local boneyards routinely crush stuff that's much more than 10 years old.

Trying to get the computer to throw a code is a good idea. It did this once when it was started it but forgot to re-connect the IAC. I took that as a good sign but can certainly try with other sensors as well.

The fuel pressure does stay up for a little bit after the pump goes off. From what I have read, that's a correct indication as the system is designed to bleed off fuel pressure shortly after shutting down.

The MAP is connected to the original port that it was connected to before any work was done on the truck. It has been verified to be the correct port and it is indeed full manifold vacuum.

I'm not certain which truck the throttle body and injectors came from. There were three TBI assemblies involved, all from 4.3 engines. The first one came from the donor truck but I took the throttle lever off that TB because I wanted to retain the correct TV cable geometry and cruise control hook up. that TB exhibited some pretty good wear in the throttle shaft to throttle body area so it was scrapped because of that wear. So, since the TB I'm using has the throttle lever attached to the throttle shaft by way of the shaft being drilled and tapped and having a screw put in to hold the lever, I'm sure that the TB I'm using did not come from the same vehicle that the ECM came from.

Lets clarify a couple of things...The "donor engine" was out of the same truck that the ECM from but since that truck was running with a bad skip, it was used only for mocking up the driveline and engine mounts.

The actual engine in use is from an 89 S-10 with supposedly 54K on it. The engine has never been apart (at least by me) has about 150 PSI compression per hole and the casting numbers verify that it's an 89 block. That engine did come with a throttle body.

The third throttle body came from a mid 90's (as best as I can remember) Chevy 1500 w/ a 4.3. That truck ran perfectly and had 200k on it with a dead tranny. I caught wind of it just before it was headed off to the boneyard so I grabbed the ECM, TBI, Battery and some misc. parts and linkages off it before it went for it's last ride.

Given that the truck with the dead tranny was in otherwise great shape and quite clean, there's a good chance that the TB and injectors came from this truck . Possibly there are numbers somewhere on the TB that can help in the verification of that?
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  #23 (permalink)  
Old 03-16-2013, 10:44 PM
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After some carbon scraping and web sleuthing, all of the TBI stuff i currently have has been identified. Most importantly, the throttle body is P/N 17089018 which is from an 87-89 Chevy and the injectors are the blue/yellow color code which is correct for the 4.3. So, at least that's good news!
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Old 03-18-2013, 08:41 AM
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Quote:
Originally Posted by 1great40 View Post
I had been hesitant to do that because the technical support guy from Painless Performance said that even though I had a different cal pac and prom from what Painless specified,the engine probably run OK, initially making me think my problems were elsewhere.

Looking back on that statement, it's a really dumb thing to say since he had no idea what I had in there for chips so predicting anything was a total shot in the dark.

The engine is bone stock with the exception of a full dual exhaust system. Painless does specify an ECM part number, a PROM part number and a Cal-pack part number. The correct parts have already been ordered (AC Delco parts). Now my thinking is that it's dumb to think the engine will run like it should when I'm not using the parts they said to use.

Today I took delivery of a 0-30 PSI gauge to more accurately measure my fuel pressure. Right now I'm reading 11-12 PSI on a 0-100 PSI gauge, which may be slightly inaccurate.

It's a little discouraging that the three technical support guys I have engaged in this project Holley (fuel pump) Painless (FI harness) and Dolphin (gas gauge) have all given me information that's kinda bogus and has caused me to waste time (and some cash) in the process of getting this truck finished. I am far from a know-it-all but everything I have done on this truck, and I've done EVERYTHING but the final basecoat/clearcoat and the seat upholstery, has come out beautifully I am totally pleased with the results.

The difference here between what I have done and what I'm having trouble with is that I fully understand everything I have done. The other examples I cited involve my reliance on "tech support" guys for stuff I'm not clear on. Once I get by each little hurdle, the bulb goes on and I'm that much more well educated for it. But the assumption I had made is that these guys should be more well educated than me.
The key work here is "initially". The 305 PROM and CALPAC will be good enough to get the motor running, but not good enough to run right in all regimes.

Bogie
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Old 03-19-2013, 06:50 PM
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The AC/ Delco Cal Pack and PROM arrived today. I'm trying to get my hands on a wrist strap so I don't zap the things when they get installed. Somehow I have a funny feeling that it can't be this easy to fix but here's to hoping!

Fuel injection is a wonderful thing when it works and it's easy to see why so many guys opt for a carb when building backyard stuff. I'm pretty much determined to learn and make this work although it's far from the latest technology, having owned and driven TBI stuff before it seems like abig improvement over a regular carb
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  #26 (permalink)  
Old 03-20-2013, 08:36 PM
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The latest:

We installed the new PROM and Cal-pack tonight. One thing that my buddy noted was that the part number in the Delco packaging for the Cal-pack was correct but the actual sticker on the chip in the carrier was off. The GM part number I ordered was 16060836 and that's what the package says but the chip in the carrier says 16060837A. I guess this bears looking into.

We started the engine and it ran much better but still not right. The fuel spray from the injectors was more of a heavy dribble. When the throttle was opened the spray looks conical but the engine would also stumble. I installed my new fuel pressure gauge and it turns out that the new gauge showed the pressure to be at 9 PSI. I pulled out the fuel pressure regulator and increased the spring pressure and got the fuel pressure to 11PSI and the engine no longer stumbles when the throttle is opened but it just won't idle right at all, still seems rich and like I mentioned the spray from the injectors looks all wrong. I swapped in another set of injectors and the spray looks the same and the engine runs the same.

I measured the resistance of the CTS and found it to correlate pretty well with my in dash temperature gauge considering that the gauge sensor and the CTS are located away from each other. The CTS said the engine was at about 160 degrees and the dash gauge was closer to 170. I also checked the reference voltage to the CTS with the key on but the sensor connector removed and that was 5.0 volts. With the sensor connected we tried to back probe the connector and couldn't get a reading, so either we weren't getting a good connection or the CTS is grounding the reference voltage from the ECM. The reason I'm suspecting the CTS is just from some stuff I have read online, I may be all wet here. I'm learning bits and pieces but not making too much progress. Does anyone have any more suggestions? Is it time to buy some fancy diagnostic tools?
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Old 03-22-2013, 05:00 PM
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Some updates: I purchased and installed the PROM and Cal-pack that Painless performance specifies in their install manual. I think I mentioned earlier that the fact that they weren't correct was only recently discovered.
A better fuel pressure gauge was installed and it turns out that the pressure was at 9 PSI so, I adjusted it up to 11 PSI. Today I discovered that the vacuum cap that was capping off the port in the TB that was used for the vapor can had a split in it, causing a vacuum leak, so that was repaired as well. Now the engine starts up quickly and the injectors at least have a conical spray pattern however it still looks like a lot of gas and the idle speed is way high. My next step is to go through the base idle speed setting sequence again. I'm not clear on the relationship between the TPS and the IAC so, we're going to start from scratch and set it up again. If anyone has any more suggestions (excluding taking it to a reputable shop, that's the next step but I'm trying to teach myself here) chime in!
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Old 03-23-2013, 07:46 AM
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Does your system use a cam sensor for engine speed feedback to the ECM? Just throwing it out there.
I'm sure you know that a low vacuum signal to the MAP sensor should increase the fuel delivery as if the engine is under load. A low vacuum could be a vacuum leak, throttle open too far, idle air control open too much, or a bad MAP.
Any way to hook up a vacuum pump to the MAP to simulate engine load just to see if the circuit is operating. Won't tell you if the values are correct, but at least you know its making a difference if varying the vacuum varies the engine speed.
Of course it needs to get into closed loop operation, and won't until it gets the correct temp reading as I'm sure you know.
Could you get a temp sensor pigtail off of a salvage yard harness to make an adapter say six inches long? I don't know if the sensor contacts are male(pins) or female(sockets), but you can plug the adapter into the sensor. Say your sensor has male contacts(the pigtails connector has female contacts-duh). A few inches from the pigtails connector strip about a half inch of insulation from the signal wire(using the correct gauge on your wire strippers cut the insulation in two places about a half inch apart and use an exacto knife to remove the insulation between them) for a place to connect your multi-meter(alligator clip would be nice). May want to tin the wire with a soldering iron, but not absolutely necessary. On the other end of the pigtail strip and solder the ends to simulate the pins (if that's what they are) or socket terminals of the sensor(you may want to get a sensor while your at the salvage yard to remove the terminals from) to connect your harness to. You need to be careful with making the pigtail end to fit your harness connector, so that you don't damage the terminals. May want to use a drill index(wire gauge drills) to get an idea of correct size of pin size for a reference. Just don't make the pins so long that they stick out of the connector and short, or too large in diameter so that you spread the sockets too far where they might not make a tight connection on the sensor when you remove the adapter if you know what I mean.
I don't know if hooking up a digital multimeter would alter the impedance of the circuit enough to alter the voltage the computer reads. I don't think so, but if the engine speed changes when you connect it you'll know it does. That's one reason to use an alligator clip for the probing of the pigtail.
Forgive me for rambling. I was an electronic tech for about 20 years and enjoy troubleshooting. Maybe it will give you an idea that will help you debug your set-up. Sounds like your getting close. Good luck!
ssmonty
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Old 03-23-2013, 12:35 PM
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FWIW,
While sitting at the ATM a little while ago, the "Check Engine Light" came on. I had my scanner in the glovebox, and decided to clear the problem code. When I was done I thought about this thread and decided to copy the "live view" readings. Maybe they will give you something to go on. Its a 2000 4.3L with a conversion to multipoint injection instead of the central FI (poppets).
I know you have a throttle body, but some of the info may correlate to TBI.
These readings were taken with an Actron OBD II and CAN Scan tool CP9575.
ABSLT TPS % 0.0
Eng. Speed 708rpm
Calc. Load 3.1
MAF 0.72
MAP 9.4
Coolant 167
IAT 81
Ign. Adv. 20.0
ST FTRM1 varies approx 0.0-1.6
LT FTRM1 varies approx 3.1
ST FTRM2 varies approx 0.0-1.6
LT FTRM1 constant -5.5(may be why my MIL Status light came on?
Hope it helps,
ssmonty
PS Sorry I can't tell you what voltage equals 167 degrees
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Old 03-24-2013, 07:30 PM
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Thanks you so much for the response and the information. This engine does not use a cam position sensor. I have ordered an OBD 1 cable for my buddies Actron and I will have some data soon to compare with. The MAP has been tested by applying a vacuum and watching the voltage change. Also a varying vacuum was applied to the MAP with the engine running and it does change how the engine runs. Another observation was EGR activity at idle...not correct. So I did a little playing around and disconnected and plugged the EGR vacuum source and the engine seemed to run better. Then we made an EGR block-off plate and installed it. Ran about the same with the exception that the engine didn't seem to be able to accelerate without dying. I think I got a little ahead of myself yesterday and may have screwed any logical progress I was making since today it will barely run and once it goes closed loop, the idle goes up to about 2500 RPM (estimate) and it just sits there and races. I'm this close to placing a call to Vic Jr. and buying a manifold, carb and distributor!!! The next logical thing to do is wait for the OBD1 cable to show up and try to get some meaningful data. The engine is also throwing codes 33, 34 and 44 but that may be from pilot error too.

I have correlated the TPS pretty much with my in dash temp gauge and Have verified the resistance and it seems about right with the temperature.

Everything seems to be pointing to a big vacuum leak somewhere but we cant find it. I did notice that the IAC pintle is quite open at idle and since the last adjusting I did, the throttle plates are basically closed but the engine races like a banshee. Yesterday while playing with the EGR and having it blocked off, the idle speed was as close to normal as we have seem from this engine. I have confused myself now so I can only hope to make some sense out of the data this week.

Thank you for bearing with me in my ramblings. I have been building this truck on and off for about 13 years and other than this the project has come out better than I could have ever expected with some folks saying that it would probably take trophies at shows (not at all why I built it) It's just that now, I'm out of my league with this problem but I was really looking forward to running Fuel injection on this truck.
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