ENGINE POWER LOSS:   ( Bog? (v.)
Aka: My engine is gutless or is a DOG  or even stalls,   See the engine  stalls/dies page.
Some bogs, feel like dragging a  10,000 pound dead weight !

All true Bogs,
or  Hesitations, and stalls are all caused by bad Combustion.
By true bog , I mean engine related, not brakes dragging or transmission seizures slippage or clutch slip.
Combustion failure types, are plentiful: (low compression(cylinders) , bad spark and bad fueling)
This includes
, Misfiring and flooding (flood; means way too much fuel, over injecting, or over-fueling)
Bad means, wrong, weak, . or intermittent.
The Best way to solve this, is doing simple tests and gathering evidence , called Diagnosis.
Keep in mind, it could be as simple as , a fuse with an invisible hair line crack inside it (or the wrong gas cap)
Assume the best (something simple) but let the test results prove the case (reality or fate)

I also have related pages, Found on road dead (F.O.R.D)
The EGR main valve, loves to stick open (every 50k miles , Suzuki asks you to check it) this causes bad combustion and stalls at idle or at every stop , rolling up to any stop sign.

ENGINE Power loss comes in many forms:     (the most complex of topics)
Ignoring the Check engine light (or SES: service engine soon) ?
Lets do the not list first:
Not clutch slip,   not A/T slip, and not the shifter lever tip #27  bushing bad missing, or transfer case in neutral.
Not dragging brakes?, seized wheel bearings?  (the car coasts in neutral okay?)

My car has and added dash voltmeter gauge, and I can see 12volt power failures at any time.
You can get one  at Walmart that fits in the cigarette lighter hole.(at the battery rack, at rear of store)

Not DC power voltage loss, you see the head lamps dim?, as engine bogs. (car battery has discharged way low?)
The top cause are:
  1. EGR stuck open
  2. Bad need of a real Suzuki Tune up ?   or as  seen here?
  3. Loss of fuel pressure (filter new?)
  4. Cam Timing belt slipped? , see #2 above. ( a new cam timing belt).
  5. Fuel pressure regulator gone wild. (seen below)
  6. ECU got bad CAP.'s
  7. Bad fuel, not common, but gee what a shame to do all these tests for bad fuel (test it in a jar, leaked from the rail)
Power loss can be felt, to bog smoothly or  spark misfiring, which is violent.
A Bog can last just a moment, then catch up?  or is full time bogging, continuous power loss.
If the engine misfires, (shakes and is heard) at idle, we find/fix this first. (saves lots of work, fixing non-moving failures)
5 Speed cars (M/T) the shifter will shake with misfire.
A bog or hesitation can happen at throttle Tip-in (right foot action) or at any speed or any gear and for sure at wide open throttle and when the big long bog happens , this helps diagnosis.
As does, knowing that spark loves to fail ,up hills, the more load on the engine , the better spark must be !
Old spark plugs (or wires), hate hills (100 years of proof) and cold damp weather.  (gap the plugs at 0.028")
I see vast posts where every time, someone gets a hesitation, the helper says replace the $250 TPS sensor ! Dang !

Ideas and Evidence?
If the engine has full power in many other modes of operation, we tend to think gee, the engine is ok.
If the engine is ok,  then it must be bad spark or bad fueling , in that order.
Most folks lacking tools to find it, just do the long skipped tune up now, after all, it's cheap and easy.
Change one HV wire at a time ! (HV means high voltage)
I also defeat the EGR main valve now, temporally and make sure the EGR main is 100% closed
(fingering it open closed, yes !, it's now closed and ready for more bog testing.).

The ECU normally prevents all bogs, by adding fuel perfectly and advancing spark. (perfect combustion)
If it does bog?, rest assured the inputs to the ECU are wrong or has injector issues ( all actuators)
The technician asks him/herself, why is combustion wrong? (when bog  happens) answer, bad spark, or fueling wrong.
Ok , spark is good, EGR Defeated ,what next? The engine, must also breath ! and pump air.
Dang, it's 20 years old?
On old cars, we check compression first, for many reasons, (old is old) andto see how much more life does it have?
150 PSI minimum at wide open throttle. x4 (equal is best)
Same with my vacuum gauge tests, got 19" inches of steady vacuum at idle, then do the melted cat test, using same gauge.?'
Ok, engine is good, vacauum is good.

If spark is good (all new spark plugs, wires, rotor /cap)  then its fueling, but what is it?
FUELING ? issues?
Now a rule on EFI , if fuel pressure is not in spec. range (specifications) the injections will be wrong.
The ECU does not measure fuel pressure live, like on much newer cars, so that becomes my job to check it.
If pressure is too low, the engine will bog under many circumstance or stall. (say 15 PSI; wrong)
If the pressure is 60 PSI (wrong), it will flood and cause very RICH misfire. (black smoke out tail pipe?)
  Throttle body injection and Multipoint:
Ok pressure is not so good? Enter Regulator H3LL:
We check fuel pressure under all vacuum conditions, at the Fuel Pressure regulator, we make sure the regulator
does not leak fuel to the vacuum nipple, and do a vacuum nipple diaphragm leak down test for 30 seconds (@hand vacuum tool)
The 8v TBI  Regulator, is only for Altitude corrections, but I alway check this,fully with vacuum tests (for range)
The 16v MPI REG.   changes fuel pressure by THROTTLE actions.   MPI means multipoint (4 injectors)
The  16v raises fuel pressure from low pressure, 30 to 36 PSI or 37-43PSI, a 6 PSI rise at wide open throttle.
The uncertainty, is the cars present altitude. (fuel pressure drops as you gain altitude)
If the MPI reg fails, to do that, the injector WILL GO LEAN and the engine will bog.
The MPI goes to max pressure at wide open throttle ( if not, it will bog on all hills ! or before)
Ok pressure is good, this is how to do old cars, some have 3 things wrong, confounding tests and rational thought.
Do not let the beast , defeat you!  Knock over the ducks one by one and win !
Keep in mind it's really 4 engines, here and all 4 must work perfectly"as one".

The 8V TBI injector can be watched with eye balls;. does it leak,? key on 3 times, do the O-rings leak, or the injector?
Key on only 3 times ,not cranked or started 1991-98) more older years, read my injector pages.
The 16v has 4 injectors, when doing the fuel pressure tests; did you skip all 6 tests, that check for leak down and balance tests?  proving the injector are , not leaking, not clogged and are balanced?  Same $20 gauge.!
What more can fail?, lots:
 The ECU can not correct any of these catastrophic errors and faults, only you can. (cleaned injectors work best) they have 10 micron screens inside that can clog. (the pro injector shop, uses reverse ultrasonic cleaning systems)
All test pass now on my pump page, heck, same words in FSM they are....  this same link covers the fuel pump regulator...

At this point, it's a fuel loss bog, a.k.a LEAN bog. The spark plug tips are white, not black with carbon.

Lean means, for what ever reason, the ECU,  is under injecting for conditions or it has sensors fibbing .
The 8v engine has a MAP sensor actual, that does not fail (hose can easy) , short of crushing it at engine install, time.
The 16v MPI engine has more ways to fail, lots more and 3 more injectors and a MAF that can fail.
  • A Weak MAF.  (fuel pressure is perfect and all filters are clean,so.... yes, easy MAF tests)
  • Vacuum air leaks ,cause idle too lean or low speed too lean bogs.  (any leak from the MAF to PLENUM)
  • Just because all 4 injectors balance test equal on car,  don't make them good, they can be all partially clogged equally.
  • If injections were rich , the ECT might be reading wrong, not 300 ohms on a hot engine.
  • If the TPS TP pin is bad/dead or glitchy, the engine will have TIP-IN bog .(right foot tips in)
  • If the TPS idle switch was not calibrated by you , then a TIP-in bog will happen. (set late to open, wrong!)
  • If the FPreg leaks fuel , lots of bad !, no need to say what, as this causes 2 errors. "wrong pressure and leaks fuel"

Odd issues and atrophy:

  • The FPreg diaphragm loves to leak/crack on 20 year old cars, as does it jamming  inside, or random jams.
  • The FPreg is best, just changed out, on 200k mile cars . (for best play long term.)
  • The 8v reg seems to last longer than 16v, due (IMO) to 16v radical  vacuum changes on this engine.Wear!
  • O Psychosis 101. This is my word for , misfire, oxygen sensor, goes crazy mode, a serious Achilles heel deal.
  • This is a design limit  of the oxygen sensor. When engine misfires, 20 % Oxygen, hits the sensor from the exhaust port with this  air slug each misfire , and the ECU sees as lean and adds fuel and goes super rich and misfires.
  • The early cars have too much, O authority , and if it reads wrong, it can cause gross leanness at idle or light cruise.
Keep in mind you can unplug the front oxygen sensor to see if it is forcing lean conditions.
That  is my story on finding misfire issues (bogs) on this old car, or any EFI car old .
The below, are elaborations on common causes and tests.


Kinds of power loss:  (the type of bog, you have is key to the cause.)
  • Total power loss, up hills, and full loss at wide open throttle?  W.O.T  and is  Continuous.
  • Mini bogs , just bogs, then recovers slowly?  A.k.a.  Hesitation.  It recovers in 1 or 2 seconds. (the delay is the Air meters, catching up, 1 more clue)
  • Transitory bogs , or slight hesitations? hiccups, pauses?   This might be just 1/10th second bog. (TPS issues?)
  • Gross Misfire. (you can feel it and hear it) Not hitting on all cylinders? (spark failure or flooding?)
Root causes and more symptoms are:
  • Bad spark plugs, gapped wrong, bad spark wires, carbon tracked distributor cap or rotor.. Causes violent misfire. TUNEUP TIME.
  • Clogged fuel filter. (wide open throttle power is low) TUNEUP time.
  • A TPS TP sensor bad, can fail at any throttle setting (right foot). It will cause hesitation, but will catch up. TP = Throttle angle sensor.
  • Hesitation?  TPS not calibrated, or the idle switch opening too late. A late switch timing, causes your right foot to fight idle controls!( A dangerous effect , this is....)
  • Low fuel pressure, lean fuel mixtures, will show up at least, going up a hill at full power.  Less that 30 PSI pressure is a problem on these cars.
  • Misfire, is caused by many things .  (compression , spark then fueling must be good.)
  • Fuel loss bogs, will be like towing a 10,000 pound trailer up a hill.  Solid power loss and continuous. LEAN BURN causes this.
  • If the fuel pressure is too high , say 60 PSI? at the fuel rail, then the engine floods and misfires. (may stall, too)
  • If the EGR leaks, the bogging will be mostly at low throttle positions.
  • If the fuel pressure regulator is bad, fueling rates can fail at any speed and load. (or the vacuum hose to it is bad? or fell off?)
Many Idle problems  are usually just a symptom of EGR leakage.
The EGR can stick open a bit or full,  at full stuck open the engine stalls.
If the engine can't run right (EGR stuck) , idle controls fail, and is just a victim.

If your 96' + or newer car illuminates the CEL (flashing is misfire) or sets DTC code P030x (where x = 0 to 4) then car IS misfiring.
The 96' + OBD2 system can be examined for Pending P03xx codes and are real.  Look for them !
Proceed below only after the car is tuned up.  If the spark plugs TIPS, are not fouled, then most likely, the problem is bogging.

Most power loss issues, come from the below: ( in the global sense)  { IN THE PROPER ORDER !}

Caused by the EFI running way too lean: (white ,or cream colored spark plug tips):

1: A bad ENGINE , or only the timing belt slipped or the EGR  stuck open or the CAT is melted. 
A bad motor, is when it can't pump air , anymore. (mechanical failure) and Vacuum is weak at idle or vacuum bounces?

2: BAD fuel pressure. The ECU Assumes this is correct at all times, and assumes the fuel pump regulator works  correctly at all times.

3: Bad  ECU INPUTS  bad. The ECU does the injections, based on inputs only)

4: Bad ( injectors, solenoids, EGR, EVAP controls)

Not to mention bad fuel, Huh?
 Primary DC electrical power feeds to EFI, Loss of D.C electric power to the EFI, results in Stalls, not bogs.

Most popular Power loss reasons (a short list).
This are the top fails.
The Macro Reasons (Wide view of problem) reasons are: CALLED BASICS !
1: A Bad Engine , over 50 ways, to fail,  but compression tests are first. (CAT blockage, EGR stuck open, massive 16v MPI, air leaks are possible) Engine cam, timed wrong.
2: Loss of spark , or weak or timed wrong. TUNE-UP's skipped. or timed wrong.
3: Over or Under Fueling. (EFI injection malfunctions) (lots of ways, we do the tests and never try to guess)   
4: Electrical voltage  loss to any of the EFI (Electronic Fuel injection components)   including the Distributor , there are 3 fuses that power these systems. EVEN A LOOSE FUSE ! "IG-COIL, "FI" and "DOME"

If you can, find a way, to discover which of the 4 above, are causing the bog, that is a BINGO !

The tools needed to find power loss are:
Compression gauge $20
A timing light (strobe) $20
A fuel pressure gauge $20  A CARB will run with 1/2 PSI fuel pressure, or gravity fed !, This is not true on any EFI system, 28 PSI minimum is a general rule.
A $10 Walmart volt meter. (DMM)? will work great for many tests.
All that cost, is about 1 hours shop labor, so is really free. and ANY used 2 times, is PROFIT. (investment grade )

FSM means the original OEM real factory service manuals,  hit back button and read the books page.

rev.8,  lots more, too much ;