1999 S70 T5 - LTFT high Topic is solved

Post by **scot850** » 05 Feb 2015, 19:37

I know California is a big state, but there is a huge auto wreckers in Rancho Cordoba outside Sacramento called VandsAutodismantlers who specialise in Volvos and Saabs.

http://www.vandsautodismantlers.com/map ... tions.html

Perhaps a good used one is available for less money and OE?

Neil.

Post by **kallekula** » 23 Mar 2015, 10:49

Found a big leak in the one-way valve between the brake servo and the intake using a vac tester. Took it apart, cleaned it and glued it back together. Reset the codes but LTFT still rises.
Haven't smoke tested more since I don't have that equipment at home and I can't drive the car because it's not registered.
Looking at diy smoke machines on the interweb I decided to build me my own (this is not my idea/design I copied it).
Took the heat wire from an old hair dryer and wrapped it around an oil lamp wick. Put it in a paint can and hooked it up to a battery. The wick is sitting in baby oil at the bottom of the can. Think I spent somewhere around $20 on it.

Post by **kallekula** » 30 Mar 2015, 09:19

Smoked the exhaust yesterday and found a leak, but it was post-cat.
Starting to feel it might be a fuel problem now. Looking at the injectors they are orange and has the nr 9186340 stamped on them. Is that the correct injector for a 99 T5 ??

Post by **misha** » 30 Mar 2015, 13:19

My non turbo came from the factory with orange injectors.I think that they are the same for stock cars...turbo and non turbo from '97.

Post by **erikv11** » 30 Mar 2015, 13:58

9186340 is a "brown" injector and it is the right one for your T5. Not the same as the NA injector, which is yellow in the 850s and the 98 S70 anyway.

I don't have any bright ideas for the LTFT issue, good job tracking down the leak possibilities. Bad MAF readings maybe?

Post by **jimmy57** » 30 Mar 2015, 14:19

What is your fuel pressure?
0.45V for rear sensor is lean. Rear sensor at steady load moving car off idle is .62-.75 V The oxygen level should be low when catalyst is working but not w/o some oxygen content.
A good oxygen sensor will respond to a created lean or rich condition within 2 seconds. On that car front sensor lean is value over 1, actually 1.25 or more. Rich is below 1 down to .80 or less is usually observed.
The front signal read through Vida is Lambda and is a value computed from pump current and signal current. A reliable voltage range is not easy to define.
The rear sensor is a binary style and is raw voltage. The ECM supplies a 0.5 V reference and lean is under 0.5 and rich over 0.5. Usually lean is going to be 0.1V or less and rich 0.8V or more.
Pulling the booster supply vac hose off will give a large leak and be your lean mixture for sensor test. Once it has had leak for 45 seconds or more the fuel trim correction will have increased inj opening time and plugging up the leak will give a rich mixture for a few seconds. Hose removl should give > 1 on front and 0.1V for rear within 2 seconds. Plugging hose back on after it has been off for close to a minute will give .8 or less from front and send rear up to 0.8V.

I looked in pocket data books I have here and can't find injector info for B5234t3.
The turbo injectors other than R high flow versions (green) are close to the same flow rte and non turbo are very much lower and the car would have other issues.

draser · Post by **draser** » 30 Mar 2015, 17:33

A positive LTFT indicates ECU is adding fuel, so you still have a leak somewhere or MAF over-reports. Leak can be anywhere after MAF, all the way to just before sensor in the exhaust. Look at STFT at idle, should be positive at idle as well, if it declines with revs then it's a leak.
More boost than normal will create a similar condition, can your scanner read boost?
If you post MAF readings perhaps someone else, having a good running similar car, can post his for comparison.
Any codes yet, freeze frames?

draser · Post by **draser** » 30 Mar 2015, 17:45

Low fuel pressure (like said) and clogged injectors are also causes - on the fuel management side.

Post by **misha** » 30 Mar 2015, 19:21

jimmy57 wrote:...0.45V for rear sensor is lean...

0.45V is right on spot for stoichiometric ratio 14.7:1
<0.45v=lean
>0.45v=rich

Post by **jimmy57** » 01 Apr 2015, 21:08

Agreed for untreated exhaust gas, the gases after catalyst treatment are not gauged in the same way based on O2 sensor voltage. After CO, HC, and O2 are catalyzed into H2O and CO2 plus a minor fraction O2, the O2 level will be lower than the level found at stoichiometric untreated exhaust gas level.