1998 S70 T5 poor running [ECT connection]

Gerd · Post by **Gerd** » 27 Mar 2020, 06:51

Hey guys. Looked at the site many times over the years but this is first post.
Vehicle is a 1998 Volvo S70 T5 with low mileage - 218 km
Started out with a thermostat going on me and I replaced it with an aftermarket one
Then thought I should replace Temp sensor too so ordered an OE one from FCP
Coolant reservoir was leaking a bit so replaced that as well - OE from FCP with new cap.
This sounds like a coolant issue but ... it isn't

During this time of changing out coolant parts, the car also became difficult to start. The colder it was, the more cranking it needed. At first I thought I had contaminated fuel and gas line was freezing up. But that isn't it as after I added gas line antifreeze and was driving it, I noticed the fuel consumption was maxed out coming off a dead stop - 50l/100km. On the hwy, it drops to 5-10l/100km. Plus it doesn't have a lot of jam unless I kick in turbo.

I figured MAF was gone and ordered a new Bosch but FCP out of stock and no time frame on getting one in so took a Bremi. As soon as I started the car, I got a code - P102.
So I went to a shop I know and put a used Bosch in there and got same result - P102.

So I figured my MAP might be dirty and cleaned it with MAF sensor cleaner but that made no diff. I am thinking maybe the MAP is just kaput from being 22 years old or maybe it is my fuel pump.

I have no codes with the way it is now so that is why I am leaning towards new MAP sensor.

My bet is someone here will recognize issue right away but for life of me, I can't put my finger on it. Of course with the coronavirus out there now, I am house bound until things get sorted. Any ideas?

Thanks

Gord

Gerd · Post by **Gerd** » 27 Mar 2020, 12:37

Tried to post once and ... disappeared. So here goes 2nd time.
1998 Volvo S70 T5
No codes. Originally thought it was frozen fuel line as difficult to start in the cold.
Then I noticed it using a lot of fuel off of dead stop - maxes out at 50L/100Km. Drops down to 4-11 on hwy. Not a lot of power unless I kick in turbo.
Thought MAF sensor and tried to order a new Bosch from FCP but they were out of stock so took a Bremi. As soon as I started the car, I got the P102 code. Swapped it back and went to a shop and put in a used Bosch - same thing - P102. Ok, now that is weird.
Thought maybe MAP sensor. Cleaned but no diff in how car runs. So still might be a MAP sensor. Or a fuel pump...?
hard to check things with Coronavirus everywhere and things shut down.
But any ideas?

Thanks

Gord

Post by **erikv11** » 27 Mar 2020, 12:42

Check the little vacuum elbow on the passenger side of the intake manifold. Super common.

Vacuum leaks will cause it to run rich. Mush of the rubber hoses are more than 20 years old.

Gerd · Post by **Gerd** » 27 Mar 2020, 12:44

Been changing out hoses but will have a look where you are talking about. Can't recall which one but will now better after I get hood open. Thanks

Post by **misha** » 27 Mar 2020, 13:24

Didn't read that anywhere in the process you disconnected negative battery cable for about 10-15min to reset ecu and fuel trims,after Maf replacement.
Bremi or anything aftermarket will not work...except oem Bosch.

Rich running condition will show with black smoke from the exhaust at idle.
Maf failure will make rpm hunting up & down.
50l on instant trip computer from a stop is normal.
If there is no black smoke from the exhaust followed with high smell of raw and unburnt fuel there is no indication that car is running rich.
Hard start when cold should be ECT sensor or it's connector.
They get corroded on both sides...ect and wiring loom side...check for corrosion and clean.
Use only oem Volvo ECT since nothing else will work....it stands for EVERY sensor.

Post by **RickHaleParker** » 27 Mar 2020, 14:29

P0102 Mass air flow (MAF) sensor.

Possible source

Fresh air hose damaged or loose. (Be sure to look in the folds of the bellow)
Defective fuse 11B/2
Contact resistance in Electrical terminals.
Short-circuit in signal cable: Signal, Power or Ground
Open-circuit in signal cable: Signal, Power or Ground
Defective mass air flow (MAF) sensor

My 1998 C70 would not start in cold weather it it was the barometric pressure sensor crapping out but that does throw a code. On the 1998 C70 it is located next to the right side hood latch.

What OBD reader are you using? You might want to try 850 OBD-II. It can get to more Volvo codes then a generic OBD reader.

Post by **erikv11** » 27 Mar 2020, 15:44

Mods this is a double-post please merge.

Gerd · Post by **Gerd** » 27 Mar 2020, 15:46

Ok, not a long list to go through. Get at it on the weekend. Looked at vacuum hoses and all seemed okay.
Thanks for the help here. Much appreciated.

I also seem to have posted the question twice so I need to sort out why one went up immediately and the first had a delay.

Gerd · Post by **Gerd** » 27 Mar 2020, 16:53

Yeah, I put a new Volvo ECT sensor in with aftermarket thermostat. The problem isn't that it is running rich but rather the ECU isn't getting right info or is kaput. Indications are showing up on dashboard computer for fuel burn, going through tanks of gas sooner than ever and the weird quirk is no codes.
Had battery out when it was -30C for a week or so, so that would reset anything electronic. But didn't disconnect when I tried different MAF sensors. Had a used Bosch MAF in to test it and it gave me 102 code right away. So put my Bosch back in. So again, that is weird. Car actually runs fine with exception it is lacking in power now, maxes out fuel off a dead stop and overall burning more than ever before.
Gotta be something odd as the colder it is out, the more difficult it is to start. I don't recall 50l/100 on the computer before ...?
I'll look at receiver end of ECT connector to make sure it is making good contact.
Thanks for info.

Post by **abscate** » 27 Mar 2020, 18:38

Merged, probably created some funny post ordering