Hi, I've a '92 4.9litre that's giving me some trouble. The car starts fine and runs fine then all of a sudden loses power like it's running on 4 cylinders. It starts chugging and backfiring and then dies. After about 15 minutes it starts and runs fine, but the problem is re-occuring. Numerous codes appear. Codes present are EO 16,21,26,31,38,52,71,73,74,99 I0 34,39,52 Any help would be greatly appreciated.

Thanks

Hi, I've a '92 4.9litre that's giving me some trouble. The car starts fine and runs fine then all of a sudden loses power like it's running on 4 cylinders. It starts chugging and backfiring and then dies. After about 15 minutes it starts and runs fine, but the problem is re-occuring. Numerous codes appear. Codes present are EO 16,21,26,31,38,52,71,73,74,99 I0 34,39,52 Any help would be greatly appreciated.

Thanks
Numerous codes imply bad battery cables/connections or/and bad grounds. Start there. Put a jumper-ground to the engine block, see if it helps. Clear the codes.

You've got quite the codes there... lets see what we've got:

E= engine/powertrain

E16- Voltage Out of Range [ALL SOL] - could be a bad voltage regulator, or many other things. Press "information" on the dash until it displays elecrical system voltage, it should stay between 13.8 and 14.7 volts while driving.

E21- Shorted TPS Signal [VCC] - TPS may be toast or bad connection, could cause bad driveability, rough running, failure to idle, bad gas mileage, among other things.

E26- Shorted Throttle Signal Switch - look above. Becuase of the 2 codes, I would inspect the wire harness for damage, most likely the TPS needs to be replaced... not too bad, just make sure you adjust it correctly.

E31- Shorted MAP Sensor- I recently replaced this on my 4.9 Its cheap and very easy to replace. It would cause bad gas mileage, rough running engine, slow response etc...

E38- Open MAT Sensor Signal- saying there is an open for the MAT sensor... this could also be in part to the E31 code, which I would try to fix first and see if it comes back.

E52- PCM Memory Reset- battery has been disconnected or went dead... no big deal.

E71- Intermittent MAP Signal- Another MAP code, exactly what it means, either the connection is bad, or more likely the MAP sensor is bad.

E73- Intermittent Coolant Sensor Signal- hmmm, kind of an odd one... First I would reset the codes and see if it comes back, if it does, then I would check the harness for damage, otherwise the coolant temp sensor may need to be replaced.

E74- Intermittent MAT Signal- read above.

E99- Cruise Control Servo Applied, Not in Cruise- Not a big deal, sometimes it gets a little hiccup, just saying the cruise servo motor got energized but it wasn't in cruise. Does cruise control work? nothing to worry about.

I= Instrument panel:

I34- Loss of Powertrain Control Module Data- Most likely related to the E52, memory was reset when battery was disconnected... no biggie, reset codes and see if it comes back.

I39- Loss of Road Sensing Suspension Data - same as above

I52- Keep Alive Memory Error- most likely related to the other memory issues.

So, here is what I would do... replace the MAP sensor and the TPS. Both are common wear items and if the car has over 100k, really should be replaced anyway. The MAP sensor is about $35 and the TPS is about $50, MAP is super easy to replace, TPS requires Torx sockets and could be a little tight, but not too bad. I would reccomend picking up a factory service manual (ebay) for exactly how to adjust the TPS, as you'll need to put the car in diagnostics mode and go to the TPS voltage output and adjust the TPS to be within spec, otherwise it will not operate correctly.

Replace the MAP sensor and the TPS sensor, then reset all codes and see what comes back... I don't think they will, maybe that coolant temp sensor code if there is really a problem with it.

A bad TPS and MAP sensor could definitly be causing the problems you are experiencing.

Do a search for rodding out the EGR tubes on the 4.9, its important to do, takes about 5mins, and is free, yet really helps the enigne. Basically remove the air intake stuff, open the throttle valves and there are 2 tubes sticking up, using a stiff metal wire (unbent metal coat hanger) rod out both tubes until there is no more stuff inside them... let it fall to the bottom, its ok. Make sure to reset the computer (disconnect the battery for a minute) before starting the engine, start it afterwords and let it idle for a couple minutes, then drive it, needs to do the idle relearn process. Also if the throttle body was never cleaned, that would be a good time to do it.

If you're not disconnecting the battery yourself, then I'd suspect a loose ground or bad cable first. Seems this would cause most, if not all, of the codes you're seeing.

The E52 code could have been months and months ago, and if not reset, it'll stay there.

Thats why its not a big deal... battery replacement, bettery died, battery disconnected etc... its just basically telling you the car did not have power at one point.

thats WAY too many codes ...all that stuff cant be bad ....im with the others here ....check all batery cables and chassis grounds , id also take a look at all fuses and the connectors at the PCM