Ask GTP About Your Car Problems/General Questions

[opelgt1969]

Can temperature differences of 15-20 degrees Celsius account for a fuel efficiency difference of 1.0L/100km? I had 8.0L/100km last Summer, and that would have been with a dodgy O2 sensor and all, and now that everything is supposedly good, all new sensors everywhere, I'm getting 9.0L/100km. The only differences are that the temperature has dropped rapidly as it's now Winter. Unless my spark plugs or something bigger is now failing.

Short answer Yes. I have a 1973 MG Midget that has dual carbs and I can tell the difference between driving the car when the temp changes. The other thing is the fuel expands with heat so 9 liters in the summer might equal to about 9.1-9.3 liters in cold weather (Don't use these numbers as true but as a guess).

 

[Paulie]

What I want to know is though how much of an effect can it have? I know it has some effect, also due to the denser air the computer throws in more fuel to keep air:fuel ratios the same. But I don't remember having such large drops in economy last year. A sports exhaust normally improves economy doesn't it? A good one anyway. Or maybe my computer is spazzing out with the larger intake and exhaust and just throwing in heaps of fuel. I'll know in a couple weeks when I get an aftermarket ECU and dyno tuning done. Otherwise I've got a bigger problem.

 

[niky]

Unless your engine is bogging at low rpms from a too-large exhaust, it's probably not the exhaust... but on an EFI car, improper intake modifications can alter MAF readings enough to affect fuel economy.

 

[nk4e]

Gahh....After putting in gas today after work. I notice that there is a white ring around the gas tank and when I try to shut the door. It won't close, I am currently searching the web for a solution? anyone got any ideas on how to fix it. I may hit up pepboys tommorrow before I go to work.

nvm, I solved this one. I have to go to the dealership or the junkyard.

 

[Paulie]

Unless your engine is bogging at low rpms from a too-large exhaust, it's probably not the exhaust... but on an EFI car, improper intake modifications can alter MAF readings enough to affect fuel economy.

It may be the larger throttle body then. When I have it tuned, will this be able to be solved as they'll be tuning to what's on the car? The exhaust was a performance improvement from the word go, even at lower rpm.

 

[niky]

It may be the larger throttle body then. When I have it tuned, will this be able to be solved as they'll be tuning to what's on the car? The exhaust was a performance improvement from the word go, even at lower rpm.

Normally you don't have to retune for a throttle body... but if it's big enough, it might cause a difference.

Yes... tuning will definitely help.

 

[kikie]

I have some issues with my Mondeo.

The Mondeo has a double door locking mechanisme. In the autumn and winter, when the t° drops below 13° C (55.4° F), the locking mechanisme starts to behave strangely. It always locks/unlocks itself automatically when I'm driving.

Another annoying thing is that the left headlight (Xenon) won't switch on when the air t° is higher than 28° C (82.4° F).

 

[Paulie]

What year model is it?

 

[kikie]

2002

I forgot to mention this. When it's cold outside I can't open the boot lid from the inside (button on the center console) anymore, nor does the switch on the boot lid work either. When it's warmer than 13°, everything works like it should.

 

[Paulie]

Bugger, I'm not sure if we got that model in Australia, otherwise I could have asked the Ford mechanics at work tomorrow, despite the fact I would never let them touch my car.

It's either a simple case of something contracting too much in the cooler weather, or if your car has an outside temp sensor, maybe it's something to do with the BEM?

 

[Rotary Junkie]

Ask anyway. Just because you didn't get the exact model does not mean the same issues haven't been seen before.

To me it sounds like the switchgear isn't liking itself much and expansion/contraction from temperature differences are causing it. (Probably a ballast for the HID not working as well)

 

[kikie]

It's a Ford Mondeo ST220 from august 2002.

I don't get it. A Mondeo is a Mondeo. Diesel, gasoline, 2.5 V6 or an ST220 in my case, these cars are basically all the same. So, I guess that "Mondeo" from the year 2002 should have been enough.

This post is because I don't get it what information I should have given besides; Mondeo 2002.

No pun intended with this post.

 

[Paulie]

Nobody asked for more details than a 2002 Mondeo. It's pretty busy at work at the moment because my supervisor is away which leaves......just me, but if I think of it I'll ask them.

 

[kikie]

I was talking to Rotary Junkie, not you Paulie.

And yes, my car has an outside temperature sensor. It's located under the right headlight.
This sensor shows the outside t° on the dashboard.

 

[Paulie]

Ah sorry I forgot today, geez it can get stressful when you're in charge and not really trained for it or have the authority to do certain things.

RJ was talking to me, saying that just because I didn't get an '02 Mondeo (which I may have, I didn't even check that) in Australia, I should pose the question anyway in case other Mondeo models or vehicles have had similar issues.

 

[Jondot]

Whoops, forgot this was here.

Thats stupid as a regas will cost about 70 quid and a pipe aint to much but labour is mental.
Future tip... Never go to sh@fit.
And a AC system loses 10% of It's gas a year, Hit below 60 and It won't work.

Exactly! And amazingly that wasn't even including the re-gas, that'd be another £50 on top.


Anyway, I return with a slightly related problem: the heater is jammed on furnace warm. And it's summer. And I have to be on a ferry by 5PM tomorrow.

Any way I can just disable the heater temporarily? I've looked through the manual and (unhelpfully) none of the fuses are associated with it so I can't yank any out. And if I don't find some way of stopping it then I have a horrible feeling various bits of the car are going to start melting as I drive down the motorway tomorrow. Hell I only drove it for 10 minutes today and the fascia around the radio had already started to feel like the inside of a microwave pizza.

 

[Duke]

Find where the coolant lines get piped through the heater core. It will be a pair of 1-inch/25mm hoses that disappear into and reappear from the firewall. Disconnect these from the fittings where they join the firewall and connect them together with a proper-size coupling and some hose clamps, taking care to avoid getting air into the system. Ziptie the loop to something so it doesn't fall down where it shouldn't.

 

[Paulie]

Does anyone know what percentage increase shootout mode on dynos normally increases the power by? I.e. Makes the power look like more than it really is.

 

[niky]

Does anyone know what percentage increase shootout mode on dynos normally increases the power by? I.e. Makes the power look like more than it really is.

What dyno?

If the "Shootout Mode" renders readings into BHP, it'll make it look like more power... Most dyno operators can fiddle with the SAE corrections and BHP-WHP conversions (called torque conversion factor on the dynapack), which gives them lots of leeway in interpretation.

But I don't know of any reputable manufacturer that builds dynos specifically to over-read if you push a special button.

 

[Paulie]

It's from Dyno Dynamics. Is BHP considered the horsepower at the engine? I've never known the difference between horsepower and brake horsepower.
I thought Shootout Mode was something they used to make power figures look bigger at car shows and what not.

Edit: Never mind, Jay has explained the correct meaning of it all to me.👍

 

[niky]

It's from Dyno Dynamics. Is BHP considered the horsepower at the engine? I've never known the difference between horsepower and brake horsepower.
I thought Shootout Mode was something they used to make power figures look bigger at car shows and what not.

Edit: Never mind, Jay has explained the correct meaning of it all to me.👍

So it's a WHP to BHP conversion? Don't like those. Take too many externalities into account if the conversion is operator-defined and still has fudge in it if the correction factor is done through the coastdown test.

Much better to state in WHP, as that, ultimately, is what's important in real life... the amount of power that gets to the ground.

 

[Paulie]

No no it's all in rwhp, it has nothing to do with horsepower at the engine.

 

[niky]

Oh. So what's Shootout mode then? Interested, we don't have DynoDynamics in this country.

 

[addictions]

Whoops, forgot this was here.



Exactly! And amazingly that wasn't even including the re-gas, that'd be another £50 on top.


Anyway, I return with a slightly related problem: the heater is jammed on furnace warm. And it's summer. And I have to be on a ferry by 5PM tomorrow.

Any way I can just disable the heater temporarily? I've looked through the manual and (unhelpfully) none of the fuses are associated with it so I can't yank any out. And if I don't find some way of stopping it then I have a horrible feeling various bits of the car are going to start melting as I drive down the motorway tomorrow. Hell I only drove it for 10 minutes today and the fascia around the radio had already started to feel like the inside of a microwave pizza.

Sorry been away on holiday.
Is It the electronic heat control or the cable operated 1?
If It's cable theres a good chance the cable has slipped through the metal clip that clips to the matrix or the lever on the matrix has moved to far and not returned causing the the heat control lever (on dash) to spring back when pressed to none melt mode.
If It's electronic heat controled well I don't want to upset you.

 

[Paulie]

Oh. So what's Shootout mode then? Interested, we don't have DynoDynamics in this country.

Ack, I deleted his PMs since then, but there are explainations on the interwebs as well. Here About halfway down where it has the big Shootout logo.

 

[niky]

Ack, I deleted his PMs since then, but there are explainations on the interwebs as well. Here About halfway down where it has the big Shootout logo.

Ah.

From the looks of it, they want to put a dent in the Dynojet business as a benchmark system for the tuner crowd.

Dynojet isn't the most accurate dyno out there... and being an inertial system, has many issues in terms of how it measures power... but it has one big plus compared to many other systems... repeatability. You can dyno one car at a number of different Dynojets, and they'll all read pretty much the same. I suspect Dyno Dynamics wants to be able to do the same by pretty much eliminating operator error, the cause of so many of the "WTF, R35 GTR 550hp?!? OMG" dyno readouts.

 

[CyborgGT]

'92 Accord, auto.

I'm getting a very rough, vibration-filled, ~600rpm idle when in any moving gear. Sometimes erratic whether in P/N or not, but intensifies in moving gears.

Fuel pump+filter, plug wires, and the entire distributor are new (Checker/Oreily refurbished, in the dizzy's case). Plugs are about a year old and have a light yellowish-white coating. A bit of oil is getting onto their threads, but not quite reaching the contacts themselves (valve cover and plug gaskets aren't yet a year old). I know my piston rings and/or valve seals are worn, the engine burns oil (very little smoke out the exhaust; if any, it's kinda white though). Injectors are all clicking away and drop idle pretty much equally when unplugged. Tried tinkering with the timing but it doesn't seem to change much either way.

I've heard a clogged cat can cause problems?

Ed. - driving to the store, it was actually smooth most of the time sitting at lights. Kinda schizo...

 

[CyborgGT]

Update

Feels like a misfire, got to the point where it would barely start, it was stuttering so bad. Noticed today the coolant was low, the lower hose looked like it had a vacuum in the system, the hose was pretty flat. Added more coolant, engine smoothed out greatly. Still little hiccups now and then. During a test drive around the block, RPM would drop to "0" and I'd get no power (misses returned a bit) unless I manually went into first gear. That condition went away after going in and out of 1st a few times. No spots in oil, no exhaust smoke at idle, but could it still possibly be a bad head gasket causing a misfire from coolant getting into the cylinders?

 

[niky]

It's possible. If your plugs have gunk on them, it's got to be coming from somewhere.

 

[J-PaP]

Anybody familiar with Liqui-Moly Engine oil? Are they any good?