I just picked up an 88 RS camaro with a 305 TBI. The car has been sitting for 18 years and I'm trying to bring it back to life. I replaced the fuel tank, pump, etc and rebuilt the TBI with new injectors and regulator. Also did a tune up, fresh oil, bled the fuel lines to make sure no particles. Tried to fire it up this morning and only 1 injector is firing. I'm not getting any signal to the injector on the right side. I flipped the harness and the other injector fires, but only 1 injector fires. I checked the fuses and they are good. I put a noid light on and I have no power. Are both injectors supposed to be firing at startup?

 

I guess I should have posted this in the TBI section.. I found a few threads there with some info and I tried a few things tonight. I have 12v+ to one side of each injector. I checked continuity from the injector terminal back to the ecm and I have a good connection. Looks like the ecm is the issue? Its also pulling a code 34, MAP sensor low, but it was at 4.90v. I don't have a wiring drawing yet and for some reason I can't download or zoom in on any of the pictures that I've seen posted. I ordered the dealer service manuals for the car but they won't be here for a few days.

 

Hi BubbaK , Wiggle the injector fuses while the car is running. My car does this from time to time and just wiggling the fuses corrects it. Also might check the wires where they plug into the injector and run to the rubber gromet at the throttle body. Those wires can break inside the insulation causing an open circuit.

I had a 88 silverado that was not working because one of the pins in the fuse block connector was broke keeping the injectors from pulsing. That truck about drove me nuts.

Just a few suggestions. Hope you find it.

al

 

Thanks Fan1701.. Unfortunately, I'm dealing with a no-start. I did verify 12v+ to the injectors, so that should show the fuse is good. I also verified continuity to the ecm on the - leg, so that should eliminate a bad wire from the ecm. Should the car run on 1 injector?

 

hey Bubba, You're on the right track, ECM controls the ground. Provided the connections are all good then replace the ECM (new versus used). Old injector on that side may have been shorted as the cause. Let's see if 34 reappears, if so then let's look for vacuum leak, don't forget EGR valve as possible source, it could be not seated fully or getting false vacuum signal from it's control, intake gaskets can be source on these as well.

 

Thanks for the info.. Vacuum leaks and EGR shouldn't come into play at this point. I haven't had the car running yet. The car is a backyard find that has been sitting untouched for 18 years. I've got a new fuel system and tune up in the car so far. The MAP code concerned me because I never had the engine running. Should the car at least idle on 1 injector? I wasn't sure if each injector fed half the engine.

 

It will need both to idle and run, it's only getting half of what it needs right now. If everything else mechanically and ignition-wise is ok then it should start if someone cranks it and you spray carb cleaner on the dead side and you manually control the throttle. Yah it could lean backfire if you're not use to that sort of thing and don't run it much more than say 10 seconds or so, oh and yah it will stink. ECM replacement will fix injector drive on that side and since it only takes about a minute it wouldn't hurt to Ohm out both your new injectors, and your old ones too while your at just so you know. Hopefully this engine was maintained and doesn't have any internal issues.

 

Thanks. I just picked up a new ecm, unfortunately its not a Delco reman, its a Cardone. The old injectors both tested out at at 1.5 ohms between the terminals. I'll check the replacements out tonight when I get home as long as its not raining.

As for maintenance, I bought it from the 2nd owner. He parked it because it had a valve cover leak and it was dripping on the exhaust. Didn't have the money to make some repairs, so it sat and ended up being forgotten. I think he is the mechanical type of person, but when I pulled the plugs it had champions it it that looked like they had a 0.60 gap on them . Car needs a lot of tlc from sitting outside uncovered for 18 years, but all things considered its a pretty good base to start with. T-tops didn't even leak. No bad smell inside at all. 2 small holes in the rear floorboards, but otherwise metal seems to be in pretty good shape.

 

Well, I put the new ecm in and I've got the same issue. Definitely something electrical going on.. lets see if I can explain - Injector plug on passenger side white & green - White 12v+ Green 12v- New Battery measures 12.2v.

DVOM on battery negative to white wire, shows 11.8v. Put my noid light on and it doesn't light when cranking. Put noid light in green terminal and put 12v+ to other side of noid light and it flashes when cranking. Put DVOM on battery + and white wire,crank the engine and I get 5v. My meter doesnt have pwm. I don't understand why I'm measuring 12v on the green and the ecm is doing its job, why isn't the light working? Should I run a new 12v+ to the injector connector or am I missing something else?

 

hey Bubba the white wire is your power and should stay battery voltage with key on and while cranking, test it with injector disconnected, just with the key on, and then again while cranking. A 12V automotive Test light can simplify things too, connect to battery negative, touch probe to battery positive and observe brightness, always move that ground probe a little while probing battery positive to make sure you've got best connection, now... key on and injector disconnected touch probe to white wire, nice and bright? now crank engine, still bright? You mentioned you put voltmeter to battery + and white wire, best would be battery - and white wire. When you tested the green wire circuit was it unplugged from the injector? You can also use test light to check green wire circuit, switch test light ground connector to battery positive, touch probe of test light to battery negative and observe brightness, touch test light probe to unplugged green connector and crank engine, it should flash just like your noid light did. When you attached your noid light to green and gave it an alternate 12V power, cranked, and it flashed, then it's sounding like that end of things are good. From what you've stated in your last tests it's sounding like the power circuit may be at fault. Make sure that white power wire terminal is not tweaked, make sure it's making full contact with the injector terminal post, make sure the connector that these terminals are in are not damaged from heat and that it's locks are seating properly. Right now it's sounding like it's either a connection issue or something causing a voltage drop in that white power circuit. You can jumper in an alternate fused power source if you want to confirm that power circuit is the problem. If she fires up then track down the cause. If so do a visual of the loom for damage and always a good first suspect would be if there's anything aftermarket like an alarm or cruise control or remote start or ?, or any repair where somebody may have used a cheap splice or non weather pac type connector.

 

BubbaK , The car will idle on one injector. It will run terrible though. Mine does this because of a bad connection in the fuse panel. The fuses fit tight but that isn't the electrical connection. The actual blades do not make very good contact with the wires. There should be two fuses for the injectors , wiggle them both. Just because a meter tells you there is voltage to the injector doesn't mean current can flow. Voltage may drop to zero when the load of the injector coil is applied to the circuit. Since you have tried changing the ecm at least you know it isn't that. You should spray some carb cleaner into the throttle body and crank over the engine. If the engine is getting spark then something should happen. Don't spend more money until you have this motor starting. Keep trying and you will find it.

al

 

Thanks guys for the info.. I'll do some more testing and probably run a new positive wire to the injector. I've played around with the fuses, wiggled the wires in the fuse box, tried tightening up the injector connector and a few other basic electrical common sense. We did have a small fire that singed the injector harness, but it was really only the plastic clips that seemed to have shown any signs of damage. The harness didn't melt and the wires aren't stiff or brittle.

 

well, I got the injectors working.. Apparently I had a fuse box issue.. Must have been working when I tested for voltage, but couldn't pass enough current to light the test light. I had the test light in the socket and wiggled the fuses and it lit. I looked closely at the terminal and it was split. I cut the wire off the fuse block and spliced in a new fuse holder. Still not running though. Sounds like timing is off, but I double checked everything on that. Short of pulling the valve cover to verify TDC. I did pull the cap and #1 plug to make sure TDC was close and it looked good. I'm going to replace the module and coil tomorrow. EGR is stuck closed, but that shouldn't matter.

 

1 step forward, 2 steps back with this car. Last night, I got the injectors firing, but I couldn't get the car to start. Tonight, I changed the ignition module and coil. Now, neither one of the injectors are firing. I don't have the ground signal from the ecm. Does the pickup coil send a signal to the ecm to pulse the injectors?

 

Hi BubbaK , that is great. You are close now I think. The module in the distributor sends a signal to the ecm to pulse the injectors. I would check every connector from the module out to the coil since you were in there. The little plug is easy to plug in wrong because its hard to reach under the pickup. Make sure you didn't bend a pin in the two distributor plugins or not get the plugins seated fully. Check the two plugins that connect to the coil. After that make sure you haven't lost power in another circuit in the fuse panel. I have done every one of those things I mentioned myself. Thanks for the update. Good luck!

al

 

Yes check those pins out carefully. Edward.

 

Thanks for the suggestions. I will double check the connections. I pulled the module out, plugged the old one back in, put the old coil back, then put all the new parts back in and still nothing. I did notice the prongs for the pickup coil on the old module were discolored but I'm pretty sure I had a decent connection. I'll check all the harness connections. I put an ohm meter on the pickup coil and cranked the engine. I had some pretty high resistance from the pickup coil, but I couldn't find a spec for it. The resistance did change when I cranked the engine, but didn't notice a big swing in value. How do you check the pickup coil?

 

I replaced the distributor tonight and I got a little rumble, but won't stay running. I think its time to pull the plugs, put some oil in the cylinders and do a compression check. This engine has been sitting for 18 years. I'm sure the cylinders are dry.. Hopefully I can make it run without having to rebuild it.

 

I took some time off and am just getting back into the car. I pulled the plugs and put some Marvel in the cylinders and let the rings soak. Then a compression check I had between 165-180 psi on the cylinders. Most in the 170 range. Put the plugs in and still nothing. Temp sensor was reading -40 so I replaced that. After tinkering with the timing, I finally got it running. It won't idle, but will run with some throttle. I am pretty positive I'm on #1tdc, but it really feels 180 out. Either that or 2 cyls aren't firing. It felt like it was choking. I'm sure the knock sensor is shot, but that shouldn't affect it when its cold. I have the exhaust open from cat back. I think I'm going to run it a few times and try to loosen things up a bit. Any other suggestions?

 

Time to get back into this project.. Made some progress. Was able to get the car to run finally. The distributor has a very small movement between when it sends a signal to the ecm to pulse the injectors. I haven't put a timing light on it yet, but I think its within 5 degrees of rotation on the distributor and its out of the injector pulse range. Does that seem right?