Mass Air Flow wiring problem. Please, please help me solve this

[Fastlife91]

Hi

I am so stressed about this situation and need it resolved, I will try and keep this short as possible


Several months ago Engine light came on reading faulty maf sensor so bought a brand new sensor and put that on.
A few days later engine light back on which read a fault in the maf wiring loom, checked wires and ends were torn so my mechanic friend , Brian, cut ends off.
Car still ran rough with diagnostics and engine light reading maf wiring fault, so Brian said the colors of the wiring looked to be wrong color and in wrong sequence, so as he had some wiring in his garage he decided to have a play changing colors over trying to get it right but just guessing as we could not find color sequence anywhere. he has put connectors on temporarily where he cut the wires to attatch the donor wire to.

Then he decided to take the 6 prong maf sensor off my car and put a 4 prong maf sensor on, he connected 4 of the 6 wires from the maf wiring harness to the replacement 4 prong sensor and put 2 of the wires ( 1 at each end) into a loop saying these 2 were just open loop and not needed, he later cut off the 2 wires, 1 at each end, he said they served no purpose anyway as they are only open loop.

The problem with the maf wiring still persists, not as bad as previously as car not stalling any more but does refuse to accelerate if revved to hard , also if car has been off overnight for example and you press accelerator it tries to stall first time so you take foot off and press gas again and it revs fine.
these symptoms only occurred right after he cut the wires so they are definitely related to the maf wiring being cut.


It has probably been around 6 months now that I have been having these problems with the maf wiring , I did have it booked in with an auto electrician several months back but didn't end up going because my friend told me he knew how to fix it but he didn't and so I feel to awkward to go back to that garage where it was booked in at and I am stuck in same situation.

Anyway he is saying we should put the original 6 prong maf sensor back on and see if that sorts it ( even though only has 4 wires now as he has cut 2 end wires off, 1 at each end , he says that won't matter because they were open loop and not needed anyway)



Any ideas on this situation ?


please help, I am so stressed about it,

Many thanks

 

[HandySparks]

Stop faffing about with amateurs. Take it to a main dealer for the marque in question and get it sorted.

 

[ruston]

Stop faffing about with amateurs. Take it to a main dealer for the marque in question and get it sorted.

Only sensible thing to do now. You do not know what other control parameters he has affected by his actions.

 

[Fastlife91]

Stop faffing about with amateurs. Take it to a main dealer for the marque in question and get it sorted.

I thought my friend knew what he was doing as he is a qualified master technician and he was talking as though he knew how to fix this problem but now it seems not as he has just wasted my time and probably complicated the situation further

I don't want to go to a main dealer as they would probably charge way too much.


How much do you think approximately an average auto electrician would charge to correct this ?


Ty

 

[Fastlife91]

Only sensible thing to do now. You do not know what other control parameters he has affected by his actions.

Hi


Please answer question above that I have also asked handysparks help on

Regards

 

[ruston]

It is a very difficult question to answer.
I would go to a respected Auto Electrician and ask him for an assessment to the degree interference to the original design.
The ECU is dependant on all signals from the various sensors on the vehicle to calculate the correct parameters for correct running of the engine, and some cases the gearbox.
The sensors have a cumulative effect on the ECU and the one that is showing the fault may not necessarily be the one that is.
The two wires he cut will not be there for nothing, unless there is a model variation.

 

[Barry White]

Standard Maf sensors are 3 or 4 wire. The Maf works by using a hot wire resistor as passing air cools this resistor its resistance changes and this is measured by the ECU and gives airflow. The temperature of the air affects the cooling of the resistor too so modern units have a temperature probe installed in the Maf( 6 wire units)

 

[Fastlife91]

It is a very difficult question to answer.
I would go to a respected Auto Electrician and ask him for an assessment to the degree interference to the original design.
The ECU is dependant on all signals from the various sensors on the vehicle to calculate the correct parameters for correct running of the engine, and some cases the gearbox.
The sensors have a cumulative effect on the ECU and the one that is showing the fault may not necessarily be the one that is.
The two wires he cut will not be there for nothing, unless there is a model variation.

Hi, thanks once again for replying.

can you please explain what you mean by '' ask him for an assessment to the degree interference to the original design ''
I am very confused by what that means ?

Is there anything that can be done to replace the 2 wires that he cut off ?


I have had extremely bad luck with cars and l have already spent a lot of money on my current car that I've only owned for about 8 months.


1st car (corsa) head gasket blew 2 months after purchase

second car (astra) head gasket blew several weeks after purchase, after that whole brakes had to be replaced, brake servo, I kept count how much I spent on repairs on that and it came to over £3,500 in 3 years, had to be scrapped in the end.

3rd car- citroen Xsara, Only had this car for 1 month and cost me £700 to buy and spent £200 on other repairs, then had a problem car would not start so after 3 weeks I bought a different car ( now my current car) , I later found out it was the fuel pump had gone on the citroen xsara.

4th car 2006 MK2 Focus 1.8 TDCI Sport , this is the car I have now. Day 1 car overheating loosing water, garage diagnosed head gasket ( but found out later that they lied and only replaced water pump), then a day after purchase light came on dash which later found out was transmission light for gearbox, then had problem with leaking fuel injectors, then turbo was faulty, then all brakes need replacing, shock absorbers replaced, both suspension arms and driver side wheel bearing and more, steering arms, EGR had to be replaced inc manifold which cost me £300, rocker cover leak, and other things too.


I work hard and struggle sometimes to keep my car on the road in a roadworthy condition, I have been lied to about non existing repairs to often and have had very bad luck.

I just want this problem with the maf sorted soon and at a reasonable price



thank you

 

[Fastlife91]

Standard Maf sensors are 3 or 4 wire. The Maf works by using a hot wire resistor as passing air cools this resistor its resistance changes and this is measured by the ECU and gives airflow. The temperature of the air affects the cooling of the resistor too so modern units have a temperature probe installed in the Maf( 6 wire units)

Hi, thank you very much

My car originally had a 6 pin sensor with 6 wires going to it from the harness. then my friend tried swapping the sensor and put on a 4 pin maf and connected 4 wires and looped the other 2, he later cut off the other 2 saying they were not needed.

Now, as this sensor still does not work he says we should put the 6 pin sensor back on and see it it works now that we have swapped the sequence of the color wires around.


Is it going to be a problem do you think that he has cut off the 2 wires that he calls an open loop or is he right that they are not needed?


is there any way to replace the 2 wires that he cut off if needs be that my car may need them ?


Many Thanks

 

[ruston]

Basically , to see if he has butchered the wiring, to be blunt.

I feel sorry for you , this is an all too common story. There are many cars that are passed through auctions etc as trade ins and have multiple problems , then passed on to unsuspecting members of the public.

As you have spent so much on your car it is difficult to let go, so my advice to you is to try and find a REPUTABLE auto electrician and see what needs to be done now.
As you have seen the problems are cumulative , and it is hard to pinpoint a cause on a forum, but abuse and lack of maintenance seems to be a problem with your vehicle.
Is it a high miler.

 

[Barry White]

You need the correct Maf fitting and the wiring put back as it was then take it to either the main dealer of a good engine specialist and have it checked. The Maf conector harnes is usually available as a repair unit as some conectors tend to corode they will need to be spliced back into the loom correctly.
Playing about swapping wires wont help it may have even damaged something else.

 

[Fastlife91]

You need the correct Maf fitting and the wiring put back as it was then take it to either the main dealer of a good engine specialist and have it checked. The Maf conector harnes is usually available as a repair unit as some conectors tend to corode they will need to be spliced back into the loom correctly.
Playing about swapping wires wont help it may have even damaged something else.

Is it possible somehow to replace the 2 wires that Brian cut off ?

 

[Fastlife91]

You need the correct Maf fitting and the wiring put back as it was then take it to either the main dealer of a good engine specialist and have it checked. The Maf conector harnes is usually available as a repair unit as some conectors tend to corode they will need to be spliced back into the loom correctly.
Playing about swapping wires wont help it may have even damaged something else.

Hi

I have the 6 pin maf sensor here but need to get hold of a plug so that I can put it back on,

I will go to a reputable auto electrician rather than a main dealer as main dealers can be extremely costly and also a reputable auto electrician is bound to have more knowledge regarding car electrics.


Is it possible in any way that the 2 wires from the maf harness that Brian cut can be replaced ?

 

[ruston]

Yes if you have room to trace them back in the harness identify them correctly,and be able to splice them,then correctly terminate them in the plug.

 

[Geordie Spark]

Yes if you have room to trace them back in the harness identify them correctly,and be able to splice them,then correctly terminate them in the plug.

........... or you could stick a couple of nice SU carbs on it. :rolleyes2:

 

[Fastlife91]

Yes if you have room to trace them back in the harness identify them correctly,and be able to splice them,then correctly terminate them in the plug.

I basically know nothing about car electrics but am just trying to get an idea.

what did you mean by '' if there is room in the harness identify them correctly and be able to splice them and correctly terminate them in the plug mean ?


Looking at the wiring harness now, there does not look to be anywhere that you could add the 2 wires back on, also the wires he cut off I do not have and also don't know what colors the wires were ?






many thanks for your help.

please reply

 

[gnuuser]

generally if the harness (loom) is not damaged too much a reputable auto electrician can trace the cabling and properly splice them.
providing they are spliced correctly (with corrosion resistant connectors or splices) using the incorrect splices can leave a weak spot that can give you trouble later.
generally its better to replace the entire harness but that can be expensive.

the main problem with modifying a harness for a different sensor is that you can end up damaging the autos computer.
they are engineered to look for and use specific signals and data to keep the engine running correctly.

although its expensive to take it to a dealer (if they muck it up then they have to fix it out of their own pockets)
this may be the best course to take when it comes to a vehicles electrical system

 

[Fastlife91]

generally if the harness (loom) is not damaged too much a reputable auto electrician can trace the cabling and properly splice them.
providing they are spliced correctly (with corrosion resistant connectors or splices) using the incorrect splices can leave a weak spot that can give you trouble later.
generally its better to replace the entire harness but that can be expensive.

the main problem with modifying a harness for a different sensor is that you can end up damaging the autos computer.
they are engineered to look for and use specific signals and data to keep the engine running correctly.

although its expensive to take it to a dealer (if they muck it up then they have to fix it out of their own pockets)
this may be the best course to take when it comes to a vehicles electrical system

What if it turns out that the auto electrician is unable to splice in the 2 wires and if I am unable to find a replacement maf wiring harness ?

 

[PEG]

Hi there,unfortunately,you took a chance on the people carrying out the previous work,presumably to save money. This is fine,and understandable.

The sometimes downside,to these chances,are the possibility of a disaster,and a much increased cost,in putting things right.

A dealership,will often,not want to get involved in such instances,beyond a code read and basic assessment. The reason for this,is they function by knowing pretty accurately,the £/Hr for the work done. To find issues,on a serial basis,after each subsequent fix,absorbs hours,and is not always a one person task.

When push comes to shove,they will get external contractors in,to farm this out. Usually on older models,or rarer ones...or with "special" customers.

This is,on occasion,when i get a phone call...and it can be a MASSIVE pain!


You,or whom ever takes the task on,will need as a minimum,the correct wiring diagram for the vehicle. This will give you the original manufacturers cable codes/colours,and termination types and positions.

This would give a decent auto electrician,a chance on rectifying the modifications already done.

At this point,a code read may yield further information,on the faults encountered.

At the stage you are at now,i feel you no longer need someone to "have a go",and have to make the decision whether or not, to tackle it properly.

Good luck,and take heart,that these things happen,and can be solved.

 

[Fastlife91]

Hi there,unfortunately,you took a chance on the people carrying out the previous work,presumably to save money. This is fine,and understandable.

The sometimes downside,to these chances,are the possibility of a disaster,and a much increased cost,in putting things right.

A dealership,will often,not want to get involved in such instances,beyond a code read and basic assessment. The reason for this,is they function by knowing pretty accurately,the £/Hr for the work done. To find issues,on a serial basis,after each subsequent fix,absorbs hours,and is not always a one person task.

When push comes to shove,they will get external contractors in,to farm this out. Usually on older models,or rarer ones...or with "special" customers.

This is,on occasion,when i get a phone call...and it can be a MASSIVE pain!


You,or whom ever takes the task on,will need as a minimum,the correct wiring diagram for the vehicle. This will give you the original manufacturers cable codes/colours,and termination types and positions.

This would give a decent auto electrician,a chance on rectifying the modifications already done.

At this point,a code read may yield further information,on the faults encountered.

At the stage you are at now,i feel you no longer need someone to "have a go",and have to make the decision whether or not, to tackle it properly.

Good luck,and take heart,that these things happen,and can be solved.

Hi.

I am trying to save money as only had this car a few months and a lot of money has been spent on it already, I spent a heck of a lot on my previous car repairs also and I want to try and keep costs low on this job n,but also want to ensure a good job is done.

I am not going to go to a dealership, I am aware the often lie and also can be extremely expensive.
I will seek out a reputable and competent auto electrician and somebody who doesn't charge too much.

I know basically nothing at all about car repairs and have been relying on Brian to do it for me, well he offered but he has probably complicated the situation. I trusted him as he si a qualified master technician but I know that this does not mean he may not know much about the electrical part of things.


How can the 2 wires be replaced that Brian cut off ? he calls it an open loop and the 2 wires he cut he said were not needed anyway but now lots of people; are saying he was stupid to cut them and that the wires were needed.
I can't see anywhere to splice them back in, can't see anywhere on the loom where they have been cut ?

Also we need to take the 4 pin maf sensor back off and put the original 6 pin maf sensor back on but we need to get hold of a plug first to be able to wire the 6 pin plug back in.



Is there any way whatsoever that we can find the correct wiring diagram for my car's MAF sensor ?


Many thanks