wolfsinc

Right off the bat, I am enthusiast, not a professional mechanic. I know mechanics, but it is definitely not my life passion. Computers and Geek stuff is my life.

So yes I want to know everything there is to know about using the Dynamic EFI (P4) Flash System for my Vette, if for no other reason then to say I can talk to my Vette with my laptop?

That topic aside though, I have to get it running good first, which I thought I had done, until things took a turn for the worse.

So I bought the Vette knowing that it had been sitting for about 4 years, and needed some work. I test drove it and it truly appeared to be basic tune up stuff, no taps, clicks, ticks, clatters or clucks. Just really rough idle, poor acceleration and an occasional stall. But for $3500 I had to have it, since I've loved Vett's my whole life and have passed up my Vette 5 times in the past.

I picked up the Vette and Drove it the 35+ miles home. It ran decent on the interstate, but I knew it was in dire need of a good tune-up and some tender love and care before I began pushing it too hard.

During the first two weeks I changed the spark plugs, spark plug wires, cap and rotor, serpentine belt, fuel filter, fuel pump relay, overdrive Relay, air filter (K&N), O2 sensor and rewired the security system/keyless entry system so it would work (someone had cut the main wire to the stock security system, most likely to install their own custom system, and they left the keyless entry system wired, but not powered.

The fuel pump stayed on all the time when I first got the Vette, this was draining the battery and of course causing the system to loose it's settings and codes, because I would either have to use the battery disconnect to spare the battery, or it would be dead within 12 hours anyway. After tracing things and changing the fuel relay I could not get the ECM to trigger a High (12 Volts) to turn on the pump. If however I ran 12 volts to the ODB1 (G) pin the car would fire up and idle great, remove the jumper the car dies instantly.

My best guess after all my diagnosis is that either the Oil Pressure switch or the ECM itself is having a problem in that circuit. I didn't have a chance to continue diagnosing that before my current problem began. I did for the time being tie the Fuel pump relay into the keyless entry ignition pin (goes high when ignition switch is on, low when off) into the fuel pump relay. This allowed the pump to be on when the car was being used and off when the keys were removed. This worked as a temporary fix. Any other thoughts on why the ECM is not kicking on the fuel pump would be greatly appreciated.

So after all the work mentioned above I had the Vette running like a champ, except for an occasional hiccup when I took off, possibly related to the clutch although it could have been electrical or fuel related as well, again I was not able to fully diagnosis this before my current problem began.

Now my current problem is that the car began running really rough and stalling when it got up to temperature, or at least that is when it appeared to have began. Then it slowly progressed to where the Vette will only run for about 3 to 10 seconds, if I am lucky.

Since this began I have done a Vacuum check, using a home brewed fog machine setup (which worked great by the way), changed the MAP sensor, rebuilt the throttle bodies and cleaned the injectors. Still no luck getting it to run. Even after the rebuild of the throttle body and cleaning the injectors the spray appears good and even, although the front one does appear to have more droplets, then the rear, but not by much. But the car would do the same thing, start and die out within a few seconds.

Of course now when I try to start it, there is no gas, so I am either out of gas, indicating that my gauge is not working properly and the gas mileage really stinks right now. I put 11 gallons in after the drive home to ensure I didn't run out of gas while I was doing the tune-up stuff. So the fact that it might be empty is troubling, but also possible especially with how bad it was running in the beginning.

Anyway I am going to change the fuel pump, with the recommended pump from a 1985 Vette. What I am trying to find out is, should I drop the gas tank and clean it out, or just clean it out as recommended by another thread on this forum?

Also where can I send my injectors to have them reconditioned and synchronized for flow (again another post on You Tube showed this being done, but they appear to be out of business now or are not responding to my emails). They indicated that they could recondition them for around $75 (not sure if that was each or not). In either case I have seen posts where this is preferred over purchasing new injectors, unless the new injectors are guaranteed to be tested as a matched/synchronized pair (which is hard to find and costs more when you do find them).

So is this accurate or should I just invest in new injectors?

Is there anything else I may be missing which would cause the car to run only for a few seconds, and then stall?

I have read and heard comments such as temperature sensors, TPS, IAC valve and bad ECM (which I am already suspecting).

I have found a mobile mechanic who might be able to come to my house and do a full diagnostics on the car, but I haven't talked to him yet to see if this is possible and how much he'll charge.

Any advice would be greatly appreciated.

Wish I had the EPL system in place now, I know the data from that would be beneficial in diagnosing this issue. But don't have the $500+ at the moment. Anyone have a used one they want to donate or sell cheap to a new Vette owner .

Sorry this post was so long, just wanted to ensure everyone had all the facts, not just my saying "Help car won't stay running for more than a few seconds." although if that is recommended in this forum for better results, let me know, I can be short and to the point as well.

Thanks all in advance for you assistance.

WOLFSinc

Nathan Plemons

Welcome to the cease-fire, catch-fire, back-fire, mis-fire, whatever you want to call it fuel injection system

In all seriousness it didn't make that much power but it did get the job done. I drive an LT1 so every time anything is wrong with it people point to the Opti, which it usually isn't. Basically what I'm saying is when somebody tells you that the 84 system is just junk and you're better off replacing it, just ignore them and move on.

In any event it sounds like you're on the right track. You know for a fact that you were getting spray from your injectors before but you're not now. I can think of 3 things immediately that could cause that.

1. No fuel
2. Bad Injectors
3. Bad ECM

1. As far as no fuel, I wouldn't go so far as to trust the gas gauge. Need to verify that, even if the answer is to just put a gallon in it from the lawnmower can.

2. For bad injectors, I find it hard to believe that they would both completely stop functioning at the same time. I guess it COULD happen but it doesn't seem likely.

3. Bad ECM. Electrical gremlins suck. You need to either invest in, or borrow what is called a "noid" light. You plug this in to your injector harness instead of the injector. Watch it while somebody cranks the car. If the light flashes than the ECM is at least trying to fire the injectors. This puts you back to options 1 and 2. If it doesn't flash then maybe it's the ECM.

That's where I would start. I'm sure others who actually own 84's can give you a lot more ideas.

qws

Go buy a FSM from Helm Inc first. Best manual you could ever invest in.
Your on the right track.

Put a FP gauge between your throttle bodies and see what pressures you have. You should be running between 9-13 psi.

I would also wire in your keyless system in correctly.

As far as the EBL P4 Flash, it won't work on yours since it was built to replace the the LT1 ECM. EBL Flash will however work, but without mods and such its not worth the money.

You can make or buy your own cable for the OBD1 and download winaldl for free to get your datalog done if you want.

wolfsinc

First thanks for the fast response, I was not expecting that.

Yeah I am working on adding gas tonight, hopefully, something about work and kids have kept me from buying a can and getting a gallon or two.

As for the injectors, I kind of agree chances are slim they both went out at the same time. Although it is possible they are not 100% which is causing the hiccup on takeoff, but I doubt that is what is causing my main issue right now. The fuel pump on the other hand could very well be the culprit. That is why it is next on my hit list, in either case many sites including this one recommend changing the pump to the 1985 to resolve several problems such as cold starts, poor idle and even decreases gas mileage. So it was already on my list.

I will buy, find or make a NOID light so I can test that. I already looked it up and it seems simple enough to make one, although for $27.00 to buy one I am not sure it is worth making one. But I will get it done.

Thanks again for the suggestions and the fast response.

jhammons01

There was a big debate over the '85 Fuel Pump versus the '84 fuel pump and I really couldn't decide either way if one had a definite advantage.

That being said, you replaced the fuel relay and fuel filter, but you've failed to address the pump just yet.

If that system drops below a minimum pressure, the injectors won't fire.

I think you have a good handle on the oil pump issue that you hot wired, but the stalling issue is FP failing and dropping below that level.

Since you are good with wiring, you should add a Fuel pressure gauge. You may not need it all the time, but since you seem to pretty handy, it couldn't hurt.

wolfsinc

Thanks for the fast response.

I have already priced and am preparing to purchase the FSM and FESM from Helm, thanks for the suggestion.

Are you referring to the fuel linkage between the two throttle bodies? If this is not at 9-13psi, should I test before the rear throttle body, where the main line comes in? if it is 9-13psi will this indicate an issue with one or both the injectors, or will this reading in theory be the same before or after the first throttle body? If the pressure before the first throttle body is less than 9-13 psi, does this indicate the fuel pump or would it be geared more towards the fuel pressure regulator?

I have the keyless entry system wired correctly, the only issue is if I remove the jumper from the keyless entry system to the fuel pump relay, then the fuel pump never comes on.

I believe this is what you are referring too. Once I get the car running again, I will be able to fully test the oil pressure switch and the entire electrical path for the fuel pump from ECM to Fuel Pump. Basically it appears to be limited to ECM, Oil pressure switch (possibly relay), fuel pump relay to fuel pump. But again I haven't gotten that far. I definitely know I should not leave the jumper wire to the keyless entry system in place too long, that is just a quick fix until I have time/money to get that done right.

Good advice on the EBL Flash system, perhaps I will wait, although at the end of the day, even with no Mods, I will end up getting it, just because I am a geek and want to see how it interacts with the laptop and what options I have available for tuning.

Keep in mind I am a geek and believe anything can be done given enough time and money, so I am interested in, and don't laugh too loud, fuel efficiency as well as pure heart throbbing power.

Thus my desire to have a system which allows me to have multiple settings, one for best fuel economy, one for tire burning torque and one for top speed. If this means changing tires, distributors, plugs, eproms and more, then so be it. With gas prices rummored to be rising to as much as $6 by the end of summer 2012, even 2 MPG mean huge saving in the long run.

Also when my 1992 Camaro RS / 350V8 was getting 12/16 MPG cty/hwy average and everyone told me that it couldn't get better, I was able to work with a local mechanic in Salt Lake City as we programmed a custom tuned eprom, through on a K&N air filter and I added a few balloons to my lead foot which all resulted in my achieving a constant 14/20 MPG Cty/Hwy average. I still have people asking what my secret is to good fuel economy and the main answer is simply, it's the balloons.

So it can be done, maybe not on the Vette, but only time will tell. I will keep everyone posted. As of now my MPG appears to be 4/9 cty/hwy, but agian I can not invision for the life of me that it will be this low once I have it running decent. I would expect somewhere in the ballpark of 11/16MPG to begin with a 12/18MPG without a custom eprom, if the overdrive system is working properly of course, otherwise 11/16 is tops at the moment.

So any recommendations on what cable to use, or will any USB to ODB1 cable work? I have researched WinALDL, but can't remember what I saw that eliminated it as an option. Guess I will revisit this.

I definitely want the data logging, the more information I have the better chance I will have at getting my Vette running like a champ.

Again thanks for the suggestions and the quick response.

wolfsinc

Awesome suggestion, I will look into adding a fuel pressure gauge immediately, I need to monitor this anyway since I've seen so many posts about the pressure being between 9-13psi or the crossfire won't work properly.

Thanks again.

Tom400CFI

Bad ECM and bad Injectors are extremely unlikely.
^Yes^. Get a gauge on it so you can see what it's doing. If you have fuel pressure, then check for spark. Report back.

The "85 pump" is way better than the stock '84 pump, however, there are pumps that are way, WAY better than the "85". There is nothing special about fuel pumps specifically from 1985 TPI's; it is a positive displacement pump rather than a centrifugal one in the '84. Point is, you can buy an ever BETTER pump for the same price so don't limit yourself to a 1985 stock pump.

Hot Rod Roy

Just to give you some encouragement, if I use some of those balloons on the loud pedal, I can get 26 mpg in my Cross-Fire '84!

jhammons01

See, now you are confusing me, I listen to you a lot....I know this isn't the thread, but can you expand on that thought??

I mean, I'm not going to disagree as I stated earlier, I couldn't decide either way during that debate.......

Talk about the better pumps that are out there and are they really needed?? The better pumps, are they just overkill at some point?

I'm listening.....

Rohn

The test to show the car is running off prom is key on - engine off the CE will blink and go steady on. If no blink it can be the prom or the ECU. If prom not touched it could be ECU. There is a malf code for ECU.

Tom400CFI

I am sorry. Dont mean to confuse.
Many times there are threads where posters recommend switching to the "85 fuel pump" because all 84 pumps suck. <that is not true and I point out that in MANY cases, the stock pump is sufficient. My point in that case is that one should diagnose Before throwing parts at it. Same as I am advising in this thread (put a fuel pressure gauge on it). However, if the OEM pump is bad, I would ne er ad use replacing with another stock pump; for the same money, you can get a far better pump. IF your stock pump is bad.

jhammons01

^^^ahhhh....that makes sense....

I didn't figure you for a "Bigger is always better" type....

and I agree with you, if the stocker is sufficient......you can always find bigger better but why if? if stock is sufficient.

wolfsinc

Tom400CFI and jhammons01,

I appreciate both of your input on this matter. Your discussion prompted me to do some more research on the matter to try and determine any logical reason why the 1985 Vette pump would be better to run oin the 1984 Vette and while it took some time I was able to find the supporting evidence I was looking for. I have shared my finding with community at the following link.

http://forums.corvetteforum.com/engi...fuel-pump.html

In summary, the 1985 Vette fuel pump add more flow making it better suited to the HP of the 1984 Corvette than the OEM fuel pump which was slightly over the recommended flow rate and somewhat short of the Max recommended flow rate for performance purposes.

So in the end I will be going with 1985 Vette pump, or other pump which is rated more closely to the performance levels needed for the 1984 Vette. Yes I am already looking into the Fuel Pressure gauge and am after doing my research going to be looking at a fuel flow gauge as well.

Again thanks for the advice and participation in this discussion.

jhammons01

That is an awesome post.....I'm not sure about your findings....they seem plausible, but that is the spark of the debate isn't it?

Rohn

BLUE1972

check the fuel filter and lines. . Also if the car sat the tank can have a lot of junk clogging the pickup. just a thought.

wolfsinc

Update: Yeah about the tank and sending unit......rust, about 1/8 inch of dirt and crap at the bottom of the tank, the strainer was literally black on the bottom. To be honest, the entire unit, pump and even the gasket looked as though it had never been removed. I have no real way of knowing, but I know that it was AC brand which according to the parts catalog is the OEM vendor the fuel pump.

Oh yeah, the tank was almost empty but the gas, if that is what you want to call it, that was left in the tank was so polluted it is no wonder the poor car wouldn't run.

So I did what one of the other posts on the forum suggested. I bought a $2 mop, a $5 bottle of Purple Power (1 Gal) (actually this my addition to the technique since I know how good this stuff cleans), a wire brush, brillo pads and rubber gloves. I siphoned out as much of the gas as possible. Poured in the gallon of Purple Power, stepped back and looked for any green or purple smog which might indicate that purple power and gas should not be mixed....as was safe, or at least I didn't loose any more brain cells than the gas alone might have killed.

I put on the gloves and reached down the tank and scrubbed with brillo pads and wire brush and then took the mop and scrubbed and continued to ring it out until all the liquid was out, than I used rags and shops paper towels to get the remaining debris out of the tank. Then I took the leaf blower and stuck it in the tank to dry everything out. One last wipe down to get the stuff the leaf blower dried and loosed up and to my surprise, the tank looked awesome, no major rust or anything. So I don't have to buy a new tank, which at first look I thought I was going to have to.

I then began cleaning the rust of the sending unit, OMG it was a pain, I even broke out the dremel and burnt through 4 of the wire brush attachments. When I was done, it may not have looked new, but darn close to it.

Now I did learn a valuable lesson in all this. When you take the actual sending unit case off to clean it out so your gas gauge will work properly, remember it is actually a wound wire around a flat curved plate and a wire brush kills it......yeah, so no gauge for awhile.

So after about 8 hours of taking things apart, cleaning the tank and the sending unit and trying to test the new pump, with the normal distractions for talking to the wife and kids. I finally decided to call it a night. My guess though it that after I get the pump working and back in, that my vette will fire up and hopefully run better than it was.

I still can't believe how bad the tank was, the last time I saw a gas tank that bad was in a 1965 Chevy belair (4 door) that had been sitting in a barn for 25 years before the owner gave it to me. I just replaced that one with one from the junk yard for $50.00.

Anyway so hopefully I will be able to get the Vette running tonight. I will post another update tomorrow.

Nathan Plemons

Sounds like a great start. Even if it doesn't fix your problem, it won't hurt, should have you some trouble down the road.

wolfsinc

Did I mention I HATE MECHANICS!!!

Sorry just frustrated, I spent all day yesterday cleaning the tank and the sending unit, killing the actual sender unit in the process, because the thing was so rusty. Have everything ready to go back in, but as always another wrench thrown in the mix, the keyless entry box is dead now. I have no clue how that happened, but it's dead, which wouldn't be a problem but if anyone truely has been following my progress, they might recall that because the ECM is not triggering the fuel relay, I bypassed it with the Ignition pin of the keyless entry. So now because the keyless entry is dead it only puts out 10V on the ignition pin instead of 12V, thus the fuel pump won't come on.

so now I have to try and figure out another option. I can am still trying to figure out why the ECM isn't triggering the fuel pump relay. I have to test the Oil Pressure switch. Reality is though I bought the car for $3500 and have dumped another almost $800 into it and honestly I have already spent money I didn't have, so I am tapped. I either have to do some major Jerry Rigging and just get it to run, which I hate doing because it always comes back to bite me in the end, i.e. possibly the keyless entry system, or the Vette sits for a month or two while my money recoops.

I have tested the fuel pump and everything appears to be working fine other than not getting enough voltage. For know I may just run a bypass switch from the battery into the car and back to the fuel pump relay. then I can shut the pump off easily to spare the battery, and maybe get to drive it for awhile before it either breaks down again or I get enough money to get things fixed the way I want too.

Man I thought I was gonna get lucky this time, I knew I had some work ahead of me, and I know I still have a lot more, but I was hoping they would come in spurts that were workable, not all the nickle and dime stuff all at once.

Ok I've vented, so I guess I'm off for the night to relax.

have a great night, guess the Vette will sit until I have time this weekend to work on it. Unless any mechanics in the Dallas area want to do some charity work and stop by the house sometime this week to help me diagnosis why the ECM is not kicking the fuel pump relay on.

Can't blame all the mechanics for not doing charity work, they gotta make a living too.

Can trade Geek work like web development, application development or computer repair.....

Ok ok I'll do the work myself, I'm not an idiot, I just HATE AUTO MECHANICS, especially when I don't have the funds I need to do things right.

Venting makes me feel so much better, even if on a forum, how strange is that.