Erratic acceleration between 1200 - 1500 RPM

[GreaseMonkey167]

Just to spark up some conversation I am a owner of a 2001 Volvo V70. I bought it with a blown head gasket.
Nice car I thought when I first saw it. I did the repair on the engine myself, and the vehicle ran for 4 months when it
overheated and started misfiring. I thought the head gasket was blown out once again so I eagerly decided to do the head over
without checking the condition of the ignition coil.

Anyway being that the head on this vehicle was previously done I decided to mark the vehicle on the timing in which it had,
not being aware the timing was off I drove the vehicle which ran for the 4 months it did. The second time I did the head over I did not bother to mill it a second time being that the car ran for only 4 months and overheated that one time.

Well all went Okay. Only to find out with the scan tool that 2 of the ignition coils were not functioning. Well I R & R those 2
knucle heads and now the idle on the vehicle is superb. The only thing is that now when the car idle/run at 1200 - 1500 RPM
it really put a beating on the transaxle.

I decided to bench test the oxygen sensor because of the air/ fuel ratio controller with my heat gun and the sensor gave a reading ranging from .16V - .6V which to me is good (not sure). So I put it back in the sweetish baby and put my scanner on it, to see the live data. sensor one read from .495V - .550V from the vehicle being cold to hot. I am trying to find out if the volts should be fluctuating between .16V -`.900V as Automotive Excellence indicate.

Now sometimes the V runs nice and other times it do not.
I am now going for the MAF I will keep yall updated, or hit me up.

[Pauloil]

interesting, have the same thing on 02 S60 at 96K. miles. starts and drives ok after 10 min, the odd acceleration happens. reverse is fine. NO CEL. on interstate accels well and shifts sharply. no axle clunks. never fluid change in tranny. oil clean. tranny fluid looks used but not bad. so what is causing erratic accel in town?

[Jake of Sigourney]

Electronic Throtle Module (ETM) notoriously fails in 2000-2001 year Volvo cars. Because of the California class action lawsuit, your local dealership might replace the module free if you have "dead spots" with sudden loss of engine RPM's. Talk nice to them. If car over ten years old, may not be covered. Watch engine tach and if erratic drops of needle while accelerating, then your ETM needs replacement.

[DGM]

I don't know if the problem is the ETM but in any case find this video showing the symptoms and how to clean it.





Do a search on this site or on the web. You will find plenty of inforrmation about it.

[GreaseMonkey167]

I tried changing the mass air flow sensor and I also tried cleaning the throttle. Nothing seems to clear up the problem
the code that comes up on the scanner is P1620. The next part I am planning on changing is the Oxygen sensor because on live data analysis the volt ranges from .525V - .495V during idle, but during acceleration it performs normal which is jumping from .825 to .205.

If I do not fix this problem soon the next part to go will be the tranny.
During idle the timing advances on cylinder #1 from 8 to 10 degrees and during acceleration it advances from 30 - 42 degrees.

Can someone tell me if this is normal.

[DGM]

Just to say that P1620 is ETM related.

P1620 "MIL requested by throttle unit"

http://www.pistonheads.com/gassing/topi ... 80906&nmt=


https://www.matthewsvolvosite.com/forums ... m.php?f=12

[GreaseMonkey167]

Truthfully this is what took place.
When I was doing the head over I had to cut the oxygen sensor wire.
On that sensor there are two ground wires one for the heater and the other goes to the throttle.

When I put the wire one way my OTC read MFR communication and the equus reads ETS irratic operation plus low fan signal,
but when I change the wires around the P1620 code disappears. I was unaware that that sensor was that much, so if I can reuse it
I will. The only thing is that using my ELM 323 to read live data the that front oxygen sensor usually reads .500V it does not oscillate, is this normal.

I think this code is a communication code so I reattached the wire so that it does not detect that code. Now the only code that came up is P0301 or sometimes P0300. Can the advance timing on cylinder #1 cause that as previously mentioned.

Thanks

[DGM]

Find the electric diagram of the O2 sensors. 7/15 is the front and 7/82 is the rear. I assume your car is N/A (Denso). With the schematic you will be able to make it right.

The two solid black wires are the heater ones. The others are for the O2 cell.

In any event find the link to the wiring diagram for your car. If you have a turbo it is page 32 (PDF).

https://www.matthewsvolvosite.com/downlo ... iagram.pdf

The use of the O2 sensor is essential to the good operation of your car especially the front one. Otherwise the car will fall on an internal routine where the ECM will supply pre-programed values.

For the last two codes (P300/P301) they are related to the cylinder #1 misfiring.

It may not answer all your questions but you have to make it right before to investigate further.