NEWBIE needs help, throttle holds back

[mrivett]

Well it wasn't the pipe.  s:-( :-( s:-( . It seems to be once it gets warm and you accelerate the thermometer drops to cold and the engine becomes lumpy. It's also really hot when I stopped after 8 miles this evening. Even the water bottle was hot. Surely this isn't normal after 8 miles?

[spit]

As mentioned above, that is something that sounds very electrical. I'd start with the connection to the water temp sensor (on the side of the engine block under that loose pipe). It may be dodgy or the wiring may have picked up a fracture. If the ECU sees a cold engine it will want to fuel in a different way.

That said, a wider fault in the wiring could be sending the ECU into a stumble mode so check everything over as best you can. Perhaps re-trace your steps if you've recently been working in any particular part of the engine bay.

[mrivett]

Thanks ill have a proper look tomorrow. Might be the case that a professional will have to look at it. I'm not particularly mechanically minded  :-) :-) :-)

[andyhull]

That wiring that spit is talking about ( from the pics ) looks dodgy already !! I am deffo no mechanic but those look taped up with lecky tape !

[mrivett]

Yes I've only just noticed that. I'll take the tape off tomorrow and have a look  :-) :-) :-)

[mrivett]

I've just had a look at the wiring to the water temp sensor. The wires where covered with heat shrink protector, not tape,  but I have cut the covered bit out and re-spliced them using automotive connectors.  I have also cleaned all the plugs/connectors that where available including the plug to the water temp sensor.

I ran it up for 10 minutes and it seemed ok but ill take it for a proper run later. The only thing I noticed was the pipe from the expansion bottle got hot in the 10 minutes i was running it and the water in the expansion bottle got warm. Is this normal?  :-) :-) :-)

[Wabbitkilla]

Well it should get warm, can't say I've measured how long it takes.
I'd recommend you take it for a drive and monitor carefully, also check the radiator is getting hot.

[andyhull]

I can tell you from all my trials and trivulations that the water gets warm from a 10 min idle. I also was worried at first but has been fine. Also dont worry too much about fluctuating coolant levels, because they do change when warm to cold etc. As long as you have a good amount of fluid in the bottle its fine, but keep an eye on it. Check it cold, and then warm   s:) s:)

[mrivett]

Thanks guys. I have never noticed the temperature of the water before. Ill report back later on how the wire splicing/connector cleaning has impacted on the engine stuttering.

[mrivett]

Hmmmm kind of partial success. Ran much better and was less lumpy. Still had 2 drops in there premature gauge over the 8 mile journey. Expansion bottle hot and connecting pipe hot. Radiator warm.  Not sure where to turn now  s:-( :-( s:-(

[mrivett]

Sorry that was supposed to say temperature gauge lol

[andyhull]

is the MIL light on ? and what temp does it max out at ?

[mrzwei]

Can you get a code reader on it? This seems to follow on from a repaired fault. If I've missed it then my apologies.

[mrivett]

The thermometer rises normally and doesn't go above half way which is also normal. Occasionally the needle drops to zero for a few seconds resulting in loss of power. The fault just occurred and was not the result of any 'fiddling'  :-) :-) :-)  

The light us on so ill guess ill have to dig the code reader out and report back. Should have done this first I guess. Doh.  :-) :-) :-)

[Anonymous]

Water temp gauge is supplied from the ecu. If your loosing power at the same time I would be looking more towards the ecu.

[Wabbitkilla]

Sounds like it could be power or earth to the ecu. The ecu needs to be bolted down to earth or it stops working (found this out recently by accident).

But I would expect other items to stop if it were power/earth. I think your next port of call is checking the plugs are all seated on the ecu, is there any damage to the wiring at the ecu? And check it's bolted down.

[mrivett]

Morning all. I have an update on my stuttering problem. Since cutting and reconnecting the wires I have not had any power flutters or any temperature gauge needle falling to zero, since the initial journey after re-splicing.

I am now turing to the Eml. My code reader came this morning and the codes are as follows:

P0135 - O2 sensor
P0141 -O2 sensor
P0155 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

I am ok on the first 2 but can anyone shed any light on the last one. Is it connected to the temperature sensor as mentioned before?

Thanks for all your help so far guys. I would have been lost without your help

Mart

[mrivett]

Doh!  Just searched for p0155 and that's O2 sensor too. Looks like an expensive week although I'm Going to do the resistor mod that will save some ££££'s  :-) :-) :-)

[spit]

Looks like you've lost all heater circuits on the O2 sensors. They are fragile and prone to fail, but all 3?   s:shock: :shock: s:shock:  

How long has your light been on? If its been a while, then its possible you've lost heater circuits over time - so its just the sign of poor maintenance! Or perhaps you've made whopping changes to manifold and exhaust system and the sensors have been removed and re-installed recently? Hassling them can cause them to break too.

If the light is more recent - and given your wiring joys - I'd be suspicious that your wiring has shorted out on the heater feeds. If you've got a test meter, try the following and report back:

- Unplug each sensor and measure the resistance across the BLACK wires to the sensor. If you're getting around 14-16 ohms, the heater circuit for that sensor is most probably OK. If they are open circuit, they're dead.
- Where sensors plug into the car's wiring harness, measure DC voltage at the socket pins that correspond to those black wires (with ignition on!). Let us know what you're reading there.

Depending on what you come back with, it may be that throwing new sensors in will make no difference or - worse - they'll go the same way   s:( s:(  So, best to do some checking before spending.

I've never looked through the wiring diagram to see if there's a blown fuse that could explain 3x heater circuits going   s:oops: :oops: s:oops:  Has anybody else done this? If not, I'll have a butchers.

[mrivett]

The light has been on for a while. I had a problem with the blownnfuse in the EVAP sensor, which I replaced and the 3 O2 sensor codes flagged shortly afterwards.  2 of the O2 sensors where changed about 6 months ago but i suspect the cowboys that replaced them (long story) only put generic ones in.

Ill do the tests you suggest and if all is well ill get some denso sensors from sparkplugs.co.uk. If I fit the resistor mod that should cause at least one of the code to disappear yesno?

Ill report back once I have tested everything

[spit]

Ill do the tests you suggest and if all is well ill get some denso sensors from sparkplugs.co.uk. If I fit the resistor mod that should cause at least one of the code to disappear yesno?

If its the sensors at fault, yes......but lets see what's what first, eh?

[mrivett]

I have just been checking the wiring as suggested. I get 14v across the pins where the black wires on all 3 sensors so that seems ok. I only get about 5 ohms across the black wires on the sensors themselves which maybe suggests I need new sensorsI look forward to any advice you guys can give  :-) :-) :-)

[spit]

Its good news that you've got a healthy voltage feed to the sensors.

5 ohms on the sensors themselves fits with your theory that your mechanics have fitted the wrong ones (unless your meter is wrong   s:wink: :wink: s:wink:  ). Why are all three reading 5 ohms though? You mention 2 being replaced but not the third one   s:? :? s:?  

There are some cheap generics out there with low resistance heater circuits. They may work in other cars but our ECU rejects them as broken.  s:( s:(  

You may need to replace these with the correct sensors.

Substituting for an appropriate resistor across the black wires is a much cheaper option, particularly for sorting out the post-cat sensor which is neither here nor there when it comes to sorting out your fuelling. Just make sure you strap/hang the resistor somewhere safe and get a good insulation wrap on the terminals so that it doesn't short against anything or melt something - it will get hot!

Some would suggest that manifold sensors should have working heaters rather than being fudged with resistors. That would be sensible but if you're on a budget you could always give it a try.....we've been known to get away with it as a long-term temp fix(!), and the sensors you currently have are effectively scrap anyway. Just be mindful that fuelling could be a little off until the sensors are up to temperature. You can always swap them out for genuines later on when funds allow.

[mrivett]

I have no idea why they all read 5ohm. The meter is new so it's probably not that.  :-) :-) :-)  the bill from The cowboys bill says 2 sensors so i guess they don't know about the third lol.

I'll put a resistor on the post cat sensor (already ordered) and ill get 2 new denso sensors for the other two. Hopefully that will solve the problems once and for all  

Thank you all for your help. I could not have fixed it without you guys and specially for the wiring testing stuff. I wouldn't have known where to start  :-) :-) :-)