X-90 engine bogging under acceleration

[Ken H]

Hope I can get some help here. I know this is a Sidekick/Tracker forum, I have a 97 Geo Tracker and go here often for it, but my problem is with a 96 Suzuki X-90, 16v. The X-90 was running fine, then boom, acceleration issue, she can't get out of her own way, Boggs down when accelerator is push. Sometimes she will recover, other times she almost stalls. Car starts easy, idles ok, check engine light on. Pulled codes with Actron scanner, P0135 (O2 sensor heater bank 1), P0400 (Exhaust gas rec flow). Looked through kick fix pages for recommendations. Came to the conclusion issue is fuel delivery. Did pressure test with HF gauge at the fuel filter. 40 pounds with key on. 42 pounds with engine running. Can't find anything about what that means on the fix kick, so I thought I would try here. I have already changed the fuel filter.
Any help would greatly be appreciated. New to this posting thing.

[fixkick]

who many doors on car? (2door has infamous bad fuel pump ground and connector is same place)

can be 2 things, based on intermittent nature.
since WOT fails its not a stuck open EGR, valve. as that can't hidden with WOT right foot action, but EGR main is a life time pain.
the MAF dies. on the fly. use the scan tool to see that. see maf flow rates, at stall, and at wot , stalling. on fly.
the fuel pressure drops. on the fly.
i pick those 2. (wot = wide open throttle)

135 means the front 02 sensor heater is dead, or wire cut to it) this can NOT cause wot stalls or fast foot stalls as the 02 is not used during those 2 events. but is a bad 02.front.
400 (the EGR is failing but if closed, and you defeat it (by pulling hose to EGR main (rear end at main) and plug the hose with a screw, the EGR is not the cause... (proves it)

spec fuel pressure. 40 key is perfect but 42 running is too high, the vacuum line to the FPreg is clogged, or the FPReg is bad. too. but is not causing stalls.. its just not regulating correctly.
your not in Denver are you (high altitude)???? or higher?
Static: 36-43 PSI, keyon, not started ( you may have to key on 3 times to build enough pressure, pump runs on 3 seconds)
Running: 30-37 PSI , idling.
Residual :25 PSI , after 1min. drop test.

---

2DOOR
http://www.fixkick.com/INJECTORS/PUMP/Pump-Ground1.jpg
is that rusty?

both 2 and 4 door.
is this corroded

http://www.fixkick.com/INJECTORS/PUMP/Tl2w.jpg

the pink wire above MUST be perfect. it and its connectors.

[Ken H]

Thanks for your reply Fixkick,

2 door coupe

Switched the MAF from my other 96 X-90 (yeah I own two of the 7,000 built) to see if that solved the problem. Same result no improvement.
What numbers should I be looking for from the MAF.

I will check fuel pressure Over the weekend. Pretty sure the FPreg is not working properly. Pulled the vacuum hose off and applied 15lbs of vacuumed with a vacuum pump and the fuel pressure at idle only drop from 40 to 38. Leak down test passes.

Not in Denver. Coastal Virginia.

Removed both rear tail lights, no ground wire. I will have to hunt that down. Maybe someone else knows it location.

I have also noticed at start up I no long get a idle up. I starts fine but idle is around 800-900. On my Tracker and the other X-90 I see high teens until engine warms.

Thanks again for you help.

[fixkick]

that fpreg is dead, its stuck open , hit it smartly ,it might wake up. and close.
most of them you can see a 10 psi drop. doing your hand vacuum test. (it must work at sea-level all the way to the highest mountain)
the most important function of the MPI Fpreg is to keep pressure across the injector, the same at all times. (this keeps a 5mS injection rate the same at all throttle actions) (and the higher the altitude, the lower the fuel pressure) my theory is that the PFreg wears a groove inside and sticks or the seat leaks.


at idle with high vacuum, its low, then when you do WOT, the FPreg allows pressure to rise greatly. this magic is assumed by the ECU and acceleration will suffer. if its bad. in your case, its too much fuel pressure, at low speeds. this might cause, high MPG or flooding and spark plug fouling,.
I bet your LTFT (scan PID) long term fuel trim is a huge minus number like -30, with pressure like that or is out of control at idle.
yours is stuck high.
wires. x90, x90,, different body same driveline. ,
oop sorry, i dont know where the fuel pump wires, are on any X90.. hard to find book for that. FSM.

IAC:
cold start, below 150F , the IAC must be open , this is what gives cold start fast idles. on 16v mpi
the IAC is just below the Throttle body.

MAF
the easy way to check any MAF, is to use any scan tool.
http://www.fixkick.com/sensors/92-95MAF/...sting.html

see my 3 graph plots
here is the better one , im plotting TPS to MAF. notice how they jibe.
bottom axis is time, im driving and shifting and doing hills,etc.
the left side vertical axis is throttle angle and MAF air flow. see the MAF hit 55 grams/sec. ?mass air flow ?
if for any reason the maf can't do that (fuel pressure good) then power will be totally limited by the weak maf.
The ecu reports dead mafs, but never weak ones.

plot 2:

[Ken H]

Ok, finally got some time to work on the x-90.

Replaced the FPreg. Put the fuel pressure gauge back on the fuel filter, keyed on, heard pump, pressure read 15 lbs. keyed on again, pressure still read 15 lb. Tried one more time, same result.

Decided to see if it would start. Turned key over and it started. Some delay to start but not much. Checked pressure, just under 40lbs.

Engine still would not advance under quick throttle. I could get it to pick up by being very ginger with the throttle.

Turned key off. Checked pressure gauge, 0 lbs.

Keyed on again, heard pump, 0 lbs pressure. Try this several more times, same result..

Turn key over, car starts.

FPreg is working, pulled vacuumed on it.

No fuel leaks, checked work and around pressure gauge.

Replace front O2 sensor too.

Hope you can help, I am at a loss for what to do next.

[fixkick]

your injectors are leaking,that test failed, the key off leak down test, it just holds or the injectors are leaking or the check valve in the fuel pump is stuck open, (or rusted)

key on , 3 times (unless lines were opened) key on 3 or many times if lines were open, and pressure must be 36 minimum..
the start car and the key on pressure what ever it was. must drop (FPreg action -vacuum caused)

that starting at 0psi is wrong, i bet you have a gauge issue, or the one of the schrader valves in the line are stuck closes. on mine there is one valve mid line that loves to do that trick.,
you can hear the pump run for 3 seconds, each key on. and the gauge must rise some, for it would not ever start.
most injectors are dead up to 20 psi.
watch out for the mid line valve. it's finicky,
if the pressure is good, running
we check the maf voltage next.
key on
1.0

[Ken H]

Update, thinking injectors or check valve also. I read some more on Fixkick.

I got some help so I could read the gauge at time of key on. Pump is running and I see 40 lbs. on gauge. As soon as pump goes off, pressure drops to zero.

I will check gauge on tracker or other X-90 tomorrow to see if it is working. Changing fuel filters on both of them.

I will check the MAF voltage. Replace MAF one year ago.
She is a stick. I will check the MAF voltage.

Originally thought cat blockage when problem began. I separated cat from exhaust pipe where cat starts to see if back pressure was issue. It did not make any difference so I didn't think it was a cat issue.

Thanks for the quick reply, hope for better results tomorrow.

I would like to post a pic of what I see for the fuel pump wire to get your feed back. Can you give me some direction if this is possible.

[fixkick]

it fails the 30 second leak down test. (this is a real failure)
does it fail with all 4 injector unplugged. is one cylinder flooding (wet spark tips)??
was replaced maf, a real suzuki maf, was it new, used or some clone FAM.
5speed transmission stick
great CAT not melted. vacuum tests also prove this out too.

photos are now smarter here.
it auto-sizes them. now. (fancy paid for app)
click gallery icon above.
then G16 engine.
click add picture.
type title
browse to photo.
add photo.
done
use links it gives for posting to it.
or just say see my photo in G16, ill find it.

[fixkick]

i just figured out , all zeros or 15psi, are from one man test.
if 2 persons, you will see it rises, but since it leaks so bad, you can't see it rise , using only one person.
the car will run with pressure wrong. but with a leak, we cant do the other tests.
the residual test fails (leak down) so the injector balance test can never be done.
you cant do the PFreg tests. either what that leak.
it all makes sense now.
your gauge is ok.
Residual : greater than 25 PSI , after 1 minute. drop test. (spec)
course the pressure must be at spec. first or the drop test is all a waste.

the FPR reg drops pressure about 6psi,running
using these rules.
http://www.fixkick.com/sensors/tests/FPr....html#spec

to find out if the pump is leaking is very hard. as the you can not pinch the pump supply line. (very hard to do)
so we find the leak by checking injectors.
and the FPreg can leak too, but yours is new. so will not leak. (but if you suspected it leaking, you can pinch its outgoing return hose during the leak test to see if it does leak , easy)
the injectors leaking is harder. (bore scope would make this easy) but do the leak down test, with the injectors unplugged
if the leak down ends, bingo bad ECU, (or its wires shorted to ground)
if the leak down still happens, try to see if the fuel is dumping to one cylinder with a flash light shined in to the spark plug hold (plug out)
if you see fuel there, liquid, then that injector is bad (unplugged)
if all injectors do not leak, then that dang fuel pump check ball is bad.

---

i suspect the pump is ok,
i think it will pass the shunt test at 60psi.
only the leak down failing suggests a leaking injector. this is the only hard problem working on MPI engines, the well hidden, injector tips.

---

keep in mind we may have 2 problems to fix. very very common.

[Ken H]

Looks like weather is going to be good over the weekend, going to look into checking the injectors.

Here is the pic link for the connector in the left rear wheel. The pink/black wire for the fuel pump is not included. It is in the wire harness that servers this connector. I am thinking about splicing in a connector to make cutting power to the fuel pump easier. I have been pulling the fuel relay behind the glove box, what a pain.

http://www.fixkick.com/bbs2/Suzuki-bbs/g...27_41.jpeg

http://www.fixkick.com/bbs2/Suzuki-bbs/g...06_47.jpeg

http://www.fixkick.com/bbs2/Suzuki-bbs/g...27_26.jpeg


If I find an injector that is leaking, do you suggest I replace all of them or just the bad one? Any opinion about using rebuilt injectors?

It passes the shunt test, 60 pounds when return line is squeezed.

Car is running with the same bogging issue, quick throttle engine Boggs, gradual throttle engine picks up fine.