- This topic has 7 replies, 3 voices, and was last updated 8 years, 10 months ago by
.
-
Topic
-
My wife has this 2002 Automatic Transmission, 3.4 l V6, Buick Rendezvous that is starting to give me a headache.
The main symptom I am noticing is throttle response… If I barely press on the pedal the vehicle accelerates as normal though if I press half or even full throttle it looses all power, it feels as though it hits the red line and fuel and ignition is cut off.
If I pump the pedal while in gear it will noticeably misfire.
When out of gear and I try to rev the engine it stops at 4k rpm which seems really low to me but then again I’m used to an 8k redline.It was throwing multiple random misfire, 02 sensor low volts, and lean fuel mixture codes.
I’ve replaced the fuel pressure regulator after checking it with a fuel pressure gauge; it needed a tune up so I went ahead and replaced plugs and wires, fuel filter, oil / filter and also the 02 sensor for the hell of it.
I cleared the codes and got a noticeable increase in power and also lost the lean fuel mixture detected code. So I started looking towards the fuel pump.
I disconnected the fuel filter and short circuited the fuel pump and drained the fuel through the filter and into a container.
I ran the pump for 30 seconds and got approximately 48 oz of fuel into the container so it seems to me that the fuel volume is there.
I then filled up the fuel tank and put some fuel injector cleaner in it, I also ran a whole container of seafoam into the engine.
I’m now eye balling the fuel injectors as a cause and also the TPS sensor though I haven’t had time to run a voltmeter on the TPS of yet.I have the fuel pressure readings from before and after the fuel pressure regulator somewhere; I will post them when I find them.
It is also worth noting that this vehicles has been to multiple mechanics who give it back with excuses (we fixed this, it’s a transmission issue, there’s nothing wrong with the vehicle…..)
It has also came to my attention the the head gasket has been replaced on this by a shade tree mechanic while in possession of the former owner, I was also told that he screwed it up and they had yet another shade tree mechanic fix that…..
Which now that I mention that I’m suspicious about the timing…. Which I’m going to have to figure out how to check since I’ve only done timing on b18 engines so far which are vastly different…….
-
Replies
-
Before the fuel pressure regulator was replaced the pressure was
44 psi off
36psi idle
36psi 1k rpm
35psi 2k rpm
32psi 3k rpm
28psi 3.8k rpmWith the vacuum tube to the regulator disconnected it read:
44psi off
37psi idle
36psi 1k rpm
35psi 2k rpm
32psi 3k rpm
29psi 3.8krpmI’ll update in a bit with the current psi.
Current:
42psi off
40psi idle
39psi 1k
38psi 2k
38psi 3k
37psi 3.8k
Regulator disconnected50psi off
42-43psi idle (was fluctuating a lot)
43-44 psi 1k
42psi 2k
40psi 3k
37psi 3.8kthe timing on this engine should be fine as for a shade tree it is a over head valve motor and he did not have to mess with it. and i would use some pliers and restricted the return line the fuel psi shoud max out ? if not i would chage the pump with all you have already done. maybe this will help let us no.
I was also thinking maybe some of the vacuum lines didn’t get hooked up properly but I can’t find a vacuum line map to save my life, it doesn’t seem like they even bothered to make a Haynes manual for this vehicle.
As for not having to touch it….. I find people touch a lot of shit they shouldn’t beer touching / don’t need to touch.
There was 3 gas lines coming and going to the tank. One went through the filter so I left it alone.
The other two I’m guessing was evap and return, I don’t know which was which so I did separate tests for each.Line 1
Idle 40
1k 42
2k 40
3k 39
3.8k 35Line 2
Idle 40 (When I started it from a cold start it fluctuated between 36-40 before it reaches operating temp.)
1k 40
2k 40
3k 39
3.8k 37win you stop the gas flow on the return side it should jump the psi up 70 psi or higher you just don,t want it to get higher than 75 psi because it can hurt the fuel injectors. if it is not doing this. as long as the lines are all open and the fuel strainer is open on the bottom of the fuel pump assembly. you most likely have a bad pump
Okay I replaced the fuel pump and you were right, thank you for setting me back on the right track.
I thought since the fuel pump was putting out enough volume that the pump was alright.Since I’ve replaced the pump all the power has came back to the vehicle and it manages to rev higher.
The random multiple misfire code has not resurfaced although I’m still getting low volts from the first O2 sensor.
I’m going to try to get the voltmeter on it tomorrow and see what kind of readings it’s putting out.Glad you are making progress . 🙂
Just to satisfy curiosity , you might try unplugging the TPS and see what changes . I expect it will throw codes , but they can be cleared .
If I understand correctly , the electronic injectors depend on sufficient fuel pressure to produce a proper spray of fuel ? If pressure is low , that does not happen correctly ?
With as much as you have worked on , with this car , I would consider replacing the fuel filter , also . The ones I have purchased were not very expensive . ( If you have not already replaced it . )
God bless
Wyr
- You must be logged in to reply to this topic.