92 Eldorado loss of power, missing after new intake gaskets

[Gossamer63]

Had a moment of brilliance/stupidity, could an undersized battery cause all of this with the ISC and check engine lights? we were aware of the fact that it was probably not the right size battery but never thought that this could cause the issues until now. Im also running a sub which will use more power. it also usually wont start if you have the lights on. Would a proper sized or maybe a deep cycle battery be worthy as a purchase to see if it is the cause of the problems? my dad mentioned that it seemed to run better while it was on the battery charger.

[Texas Jim]

What is the voltage reading displayed in the DIC when the ignition is ON but the engine is NOT running ??

What is the voltage reading displayed in the DIC when the engine IS running ??

[Logan]

Could be....

Distributor not timed correctly. There is a 'set timing mode' that is activated by jumping some pins on the ALDL.

Bad engine ground on block near starter. GM has a bulletin about this ground. This ground can 'look' ok. Really needs to be taken apart to clean.

Maybe rotted wiring in the distributor at the IC module. See attached pic.

Rotted 'green' AC coil pickup inside distributor. Same pic.

Clogged cat. You can remove a O2 sensor and install a bung fitting and measure the backpressure of the Cat while reving the engine..anything over 1.5-2 psi is clogged cat.

Bad PCM. You can tap test the PCM while the car is running...any stalling..burps..etc is a bad PCM.

Weak EGR valve causing too much EGR...see http://caddyinfo.ipbhost.com/index.php?showtopic=43143

[the gold2]

Not sure what the FPR is..? and we replaced the o2 sensor and it is running much better but got a code for ISC rpm out of range(E030 or PO30) and a code for loss of road sensing data(i039)

For is the fuel pressure regulator. Inexpensive and not too difficult to replace. Sometimes they leak without the classic telltale sign, like mine did on my 92 Eldorado.

It might be contributing. Check the ground strap like a previous suggestion.

Cheers!

[barczy01]

How was the car running before the repair was performed of the intake manifold gaskets?

[Gossamer63]

How was the car running before the repair was performed of the intake manifold gaskets?

it had similar issues but they were intermittent.

[Gossamer63]

Thanks to everyone for the input and suggestions it is running much better, we are about 95% of the way to getting it running perfectly. Well we replaced ISC and looked at the old one and it was trashed. It idles and runs much better, can still see the ISC hunting for the idle and still has erratic RPMs above 50 or 60 MPH and the power has improved greatly. I believe the ISC needs to be set, is this something I can do or not? Suggestions?

[Cadillac Jim]

If you are still running with an undersize battery, I would get the right battery in it ASAP.

If it's running irregularly at 50-60 mph, it's not the ISC. Here I would look at fuel and spark.

[Gossamer63]

Thanks, it has new cap rotor, plugs, wires and I cleaned all the connections for the coil. Could the erratic RPM issue be the TPS?

[Cadillac Jim]

When running closed loop, the DFI uses the TPS, MAP, IAT, ECT, H02, and other sensors to control the fuel and spark. If any one of them acts up, the PCM throws a code and goes into a back-up mode. The back-up mode can be open loop or closed loop, depending on the problem the PCM has detected. Since all of them affect emissions, the MIL will come on.

Can you run the codes while it is doing it? If not, you may need a code reader to see HISTORY codes.

Things that can cause loss of power and surging that don't throw a code include bad plug wires, breaking down coils, clogged injectors, and clogged fuel filter. Eventually the PCM will throw a P0300 and the MIL will come on but that won't happen immediately.

Again, I forgot you have a 4.9. I don't know anything about the mechanics of the TBI or HEI; I would ask that someone who has lots of hands-on experience with tuning the 4.9 speak up about clogged injector and other fuel delivery issues with the 4.9. The coil is inside the distributor in the 4.9 and can cost $35 to $50. Rock Auto lists two part numbers, D505A and D555A, and the description implies that this part is the whole HEI module, not just the coil, because they say that it works from a Hall effect switch or pick-up coil, which is a function of electronics. There is one red flag there: The description of the D555A says "a ground strap may be required." Check the ground connector - both ends and also look for a broken wire inside the insulation.

[Gossamer63]

Yup it is the 4.9. Currently the distributor is out, have to replace a couple of lifters, and I have gone over the wiring. All of the insulation is intact and over all the unit looks good but I will check the ground and OHM the wiring. We have tried looking for codes while this happens and after and we have had no codes. Two new O2 sensors, new MAT sensor, waiting on a new EGR solenoid and cleaned the EGR while the manifold is off, While the fuel rail is off I will take a look at the injectors ,I read in another post that you can plug in the rail, attach fuel lines and turn the key to on, it will spray fuel, I will cover the engine, but you can see if at least all of them are at least getting fuel and an idea of the spray pattern. In the end I may just have to take it in and have it diagnosed. I am not a mechanic and have an electrical back ground but that will only get me so far with out proper diagnostic equip.

[Gossamer63]

I forgot we did replace the battery with the correct battery

[JohnnyG]

For some odd reason, my Quote, Copy and Paste functions have quit working, sorry.

Anyway, when powering up the fuel pump, KO/EO the fuel rail will indeed pressurize, but the injectors should NOT spray fuel. They are powered off as default and will not spray until they are fired with another electrical supply. If any are leaking during the above process, that will be readily apparent, and cause for replacement. I remember several years ago reading that a 9V battery will fire an injector, but not sure if that is possible or safe with your car. At any rate, I'd never try to start the car while in this condition, and be very careful not to create sparks which could ignite the resulting spray of gasoline.

[Gossamer63]

For some odd reason, my Quote, Copy and Paste functions have quit working, sorry.

Anyway, when powering up the fuel pump, KO/EO the fuel rail will indeed pressurize, but the injectors should NOT spray fuel. They are powered off as default and will not spray until they are fired with another electrical supply. If any are leaking during the above process, that will be readily apparent, and cause for replacement. I remember several years ago reading that a 9V battery will fire an injector, but not sure if that is possible or safe with your car. At any rate, I'd never try to start the car while in this condition, and be very careful not to create sparks which could ignite the resulting spray of gasoline.

Thanks for the info, i think I will just skip trying to test the injectors.