1991 exp engine failure

[Pablo Sanjines B]

today I was going back home when suddenly the engine started to fail, at the begining I heard a mechanic sound then turned the engine off and re-satarted, the mechanical sound was gone but the failure remains. I was 4 blocks from home so I was able to get it there. seems to work fine in Idle but it really fails when rpms are increased. The timing belt was changed a year ago. Oil seems to be ok. Spark plugs never were changed any suggestions and comments will be appreciated.

 

[2stroke]

There is not enough description here, almost everything on the motor can make a sound. If you mean the motor was running out of power, it could very well be a fouled spark plug. If its a sound that changes with the rpm's, there is a good chance it is the timing belt.

 

[Pablo Sanjines B]

Well I started the engine several times now and there is no mechanical sound at all, the check engine light is off. You can smell gas coming out from the exhaust, meaning that the is some missing spark somewhere (I really hope that is only a spark plug), the fail remains and it is really hard to increase the rpms. there is no unusuall engine sound now
(I have a 1967 f-100 and when I test the spark plugs with the engine running I unplug one at the time and is a clear sound when one is missing can u tell me iff I can use that procedure in my exp?)

 

[mr cribb]

Explorers never had timing belts. Only a chain.

There still isn't enough information to form an opinion.

 

[Pablo Sanjines B]

Explorers never had timing belts. Only a chain.

There still isn't enough information to form an opinion.

The serpentine belt doesn’t work with the timing at all?
I will replace the full set of spark plugs and let’s see how it works (In the Haynes manual tells that the mileage to replace the spark plugs is 66K and my exp has 86K already ). This morning I made the engine run for about 5 minutes when the engine runs at idle the fail is unnoticeable , but when I increase power is very notorious. The engine cranks with no problems, the gasoline smell at the exhaust pipe is strong. I noticed that the brake light came on for 2 minutes then it turned off, there is any connection between? . The check engine light remains off. Seems that the engine coughed and obviously it suffers lack of power. I read at the Haynes manual about 20 causes to check (fuel filter, contaminated fuel, coil, spark plugs, some sensor, spark plugs cables, dirty fuel injectors, dirty air filter, timing issues and other things too). I appreciate all comments and help. thanks

 

[Turdle]

Check the vacuum lines. It almost sounds like the fuel pressure regulator quit working and is now dumping excessive fuel into the engine.
Also, check the compression while you have the spark pugs out. This may show if the timing chain has jumped.

 

[Pablo Sanjines B]

Check the vacuum lines. It almost sounds like the fuel pressure regulator quit working and is now dumping excessive fuel into the engine.
Also, check the compression while you have the spark pugs out. This may show if the timing chain has jumped.

Thanks turdle will do that also. I found the following link:
http://www.explorerforum.com/forums/showthread.php?t=204267&highlight=valve+fail

I hope not to have that kind of problem in my exp engine

 

[Turdle]

Your engine is a 4.0 OHV so it does not have the miles of timing chain an overhead cam engine would have. Be thankful! Ignore that thread-

 

[2stroke]

The strange sound could have been caused by the engine running too low rpms, and rough. Apart from what was already stated, there are 2 oxygen sensors that are known to go bad on these. They're not that hard to replace, and are almost considered normal maintenance.

 

[Pablo Sanjines B]

Well like I said I changed the spark plugs but the fail remains, it was a hard job spetially with the plugs at the passanger side of the car (they are really hard to reach) well step two will be fuel filter, step three sensors, step four hit my head agaist the wall lol. any help will be welcome thanks for the posts.

 

[Pablo Sanjines B]

Ok, I changed the fuel filter, the clean fuel went into the filter but the filter was throwing murky fuel so it was my believe the problem was that, but nothing. with the new filter the fault remains, also I tested ignition coil, with the primary bindings inside the Ohms range but in the secondary binding the readings are high. According tho the Haynes manual the reading should be between 6.5k Ohms and 11.500 Ohms, mine reads 13.500 Ohms. Today I went to a shop and checked a new coil and the reading is the same that I had. Also I cleaned the sensors and am getting out of options right now. I believe that the murky fuel has clogged some of the fuel injectors, I will check that and the compression, iff that doesnt help I will really run out of options, Any comment will be apreciated.

 

[Pablo Sanjines B]

checked the compression and all the cylinders are at the same range seems to be normal. I borrowed an Obd to make the test and it gave me code 18. According to Haynes is an spout situation here, also there is something with the tach I have to mention that the tach is dead. Also the brake light keeps on all the time (I changed the hose from the vacuum to the power brake) I found the following thread : http://www.explorerforum.com/forums/showthread.php?t=260802 and it seems to be the same problem, any other ideas about the code 18 will be appreciated, also the obd displayed some ceros codes in it any idea what does it means?

 

[Pablo Sanjines B]

Ok the previous obd check was with an incredible old OBD, it was blinking turning off every two minutes re-starting blinking again turning off so I was suspicious of the reading. the last one I used is good shape OBD. So everithing seems to be fine except for a error code 41, that means:
41 R Heated Oxygen Sensor circuit indicates system lean, right side
41 C No Heated Oxygen Sensor switch detected, right side
I have to change that and hope to finally find the solution there.

 

[Pablo Sanjines B]

Well finally problem solved the issue was the ignition control module (ICM) it was not sending information to the coil ( Coil towers 3 and 4) so the missfire was heavy. Changed the ICM and problem solved. Thanks for all comments and help posted.
Kind regards