Hesitates in 2nd gear and/or Sputters in 1st and 2nd

[Bond--007]

Hi guys. Been crawling all over the web to determine what is causing my issues. Recently got a 1997 TJ with a 2.5L, 5 speed manual.

(1) Every now and again the jeep with spit and sputter in 1st and/or 2nd gear until I press in on the clutch and give it a little gas. Then it will smooth out and run fine. This usually happens shortly after start-up no matter if it's the first start of the day or I run 6 miles to the store, spend 10 mins in there, and come right back out and start the jeep.

(2) Last night and this morning while driving to work I noticed it hesitates in 2nd gear (in the higher range before shifting to 3rd).

Recent corrections: TPS, IAC, PVC, CKS, Plugs, Wires, Coil, Cap, and Rotor (all OEM)

I'm about done with this jeep and change back to my truck as my DD. This is my first jeep.

 

[JPNinPA]

Likely your O2sensors. Likely the upstream one. Or a vac leak either a loose intake or TB. When it reaches temp it seals itself.


Are there any codes?

 

[greg92jeepxj]

Having changed nearly every sensor that is critical in terms of feedback to the pcm , that leaves just the oxygen sensor(s) and cam sensor ( CMP ) . Were there any DTC codes to indicate any of these sensors were out of range ? Are there currently any DTC's now ? A good scan tool to read live data to find out if the sensors are within range will be needed to verify all activity. Although sensors were changed , you want to know if they are reading and responding as they should since you are still having the same issues and none of the replacements have cured the problem.
I,certainly hope that all the parts are working well for your jeep as you've no doubt read how less than good quality parts cause trouble and generally cause confusion , I.E. , you change a part and believe it's good and no longer the problem but find out it's not a good part and either DOSEN'T fix the problem or creates new problems. Before replacing any more parts , please try to get some llive data readings from the sensors and any dtc's before proceeding. A good repair manual should have the ranges that the sensors are supposed to be within .
I don't want to just say something like maybe you've got a bad CMP or worn distributor when my '92 is running fine with its original CMP and distributor , you will need to obtain readings and any dtc's so you've got something to go on . One more thing to check ; make certain that your fuel pressure is in range and the fuel pressure regulator and filter are good and that no fuel line restrictions exist . If pressure is not adequate , either the pump , regulator , filter or even a leak in the line could cause this condition . Sometimes in the tank where the pump connects to the sending unit the rubber hoses are not sealing well because of a leak like a split or loose or broken clamp. Check these items the best you can . There are more things such as evaporative emmissions system that cause an over rich condition that cause your engine to bog too.
I hope this to do list helps and finds the problem for you. Don't want to see you spend more money unnecessarily . Post back your findings when you can. Thanks and best of luck . Greg

 

[greg92jeepxj]

Thanks JPNinPA , my typing is slow and your post beat me to it. A vacuum leak is very likely as this driveability problem suggests poor intake quality. A friends 3.8 windstar has similar issues and waiting for him to produce a replacement plenum.
it is best to keep it simple as JPiNinPA said and start with the preliminary checks first .
I once found a vacuum leak on my 4.0 which was just the vacuum feed for the charcoal canister . It was a strong enough leak to hurt the idle directly from the intake . I belive your 2.5 will have a similar feed.

 

[dc_jeep]

I had the same issue. A 2001 4.0 manual. Mine hesitated at start up and I needed to give it has when I started it up. I was the battery, which makes no sense. Check that the battery terminals are clean.

 

[greg92jeepxj]

I had the same issue. A 2001 4.0 manual. Mine hesitated at start up and I needed to give it has when I started it up. I was the battery, which makes no sense. Check that the battery terminals are clean.

It makes more sense than believed . When proper battery voltage is NOT reaching the PCM and alternator , a miss can certainly occur when sensors , ignition system and injection system are not working properly due to not enough current reaching them and working less than optimum will cause less than optimum performance. It has been stressed that cleaning and retightening battery connections and cleaning and tightening grounds as well is necessary for electrical system to perform properly many times in this forum and is very true. Any good shop or repair manual will stress this as well. It is always worth doing the free checks first to eliminate this possibility and. Can very well be the cause in some cases. When we assume that " no , it couldn't be that " or " I already did this or changed that " and we did not perform a performance test to check that a system is working right is when we don't find the cause and miss finding the fix or just throw in the towel.
Thanks for your real world suggestion and may be more helpful than not mentioned. It's always worth a shot. It worked for you so it could for someone else too. A friend once performed a tune up and had a miss afterwards only to find that the miss was caused by a cracked porcelain on a plug . If we check our work and perform regular cleaning when under the hood periodically it lessens the chance for this type of problem to surface .

 

[Bond--007]

Thanks for the info guys. My buddy is bringing his scanner tonight since it does real time data logging. Currently the CEL is not lit but I'll scan it to see if something is stored but wasn't critical to trip the light.

New development: Since it was chillier this morning than most, I decided to fire up the Jeep to get it warm before leaving for work. It ran in the driveway for about 7-10 mins. When I drove to work, it DID NOT hesitate, spit, or sputter AT ALL on the way to work

 

[greg92jeepxj]

Sounds like it likes a rich mixture ( shaken , not stirred :funny . This is characteristic of a vacuum leak . Un metered air is being introduced to a richer mixture. The scan readings will be interesting . I'm sure you wish it were hooked up,this morning , that would have been a great time to check the fuel trim. Will be staying tuned for the scan readings. Thanks . Greg

 

[Bond--007]

Greg, what is the easiest way to check vacuum leaks? I know I have one I can't find yet because the vents and floor doesn't work, just the defrost (I found where the vacuum hooks onto the intake, so now I need to trace it out)

 

[JPNinPA]

Bond the easiest way is to start the engine and spray WD40 or carb cleaner around points that could leak. Start with the base of the TB, then each cylinder intake point. You may even spray around vac line connections including the brake booster. Listen for a change in idle. Being this is only at start up you may need to move quickly or do it over a few days while the engine is cold.

 

[Bond--007]

JPN, thx for the info. I'll try to spray each line over the course of the weekend since it's suspose to be nice. I remembered a trick dad would use to find a tire leak with soapy water but it seemed like a bad idea since vacuum line draw air in instead of blowing out

 

[greg92jeepxj]

As suggested by JPNinPA , using carb cleaner or WD-40 is very effective and quick for finding vacuum leaks. You'll get the hang of it quick too. Yes , as soon as a leak is detected , the engine will respond by a change in idle . I haven't had much luck with soapy water spray for vacuum leaks since there is no volitile chemical that temporarily acts as fuel to temporary cause engine to race and confirm a leak so it wasn't too effective . It's better for finding ignition wires that are arcing under night or dark condition. I don't know the TJ real well but the hard emissions lines that feed the vent are generally near the passenger side of firewall where the blower motor is mounted. Not sure but I think the '97 's climate control is vacuum fed and not electric blend doors involving modules so this will be nothing more than vacuum line replacement if need be.
A vacuum schematics will be helpful but I don't know if your problem is really that involved.
Follow JP's instructions and you'll find the leak(s) fairly quick. Once repaired , either the problem is solved or process of elimination is one more step,closer to the cure.

 

[Bond--007]

Update: Last night I was able to borrow my buddies scanner. When I hooked it up, there were 2 stored codes in the system. (1) incorrect purge flow (2) Misfire on cylinder 3. I cleared the DTC figuring these may have been stored prior to me changing the purge solenoid and the cap, wires, rotor, plugs. After clearing the DTCs, I proceeded to Force Flash the PCM according to the instructions found on the forum. This morning when I started the Jeep to go to work it stip and sputter like it has been (did not let the Jeep idle like the previous mornings). It seems the issue is caused from cold start-up without letting the Jeep warm up before moving. My next thoughts are to check for vacuum leaks and possibly change out the updtream O2 sensor.... Thoughts???

 

[greg92jeepxj]

I've no comment on the force flashing , I just know that this procedure rewrites the ECU ( the PROM). Hoping that invaluable stored programs that manages things like emissions as well as injection and ignition Weren't compromised. . Well , one thing at a time but I don't think any harm was caused or you would get a no start and a steady CEL light . I don't know if the evaporative emissions canister purge valve is pcm controlled ( probably is ) on your model year but if you still got the scan tool , see if if can get live data on its activity and the live stream or cross counts on the upstream O2 to see if it's in fact switching rich/lean or hanging up , necessitating replacement. Seems Thera more chasing vacuum to follow . Was hoping you wouldn't have a purge / evap problem but they're somewhat commonplace .

 

[Bond--007]

I've no comment on the force flashing , I just know that this procedure rewrites the ECU ( the PROM). Hoping that invaluable stored programs that manages things like emissions as well as injection and ignition Weren't compromised. . Well , one thing at a time but I don't think any harm was caused or you would get a no start and a steady CEL light . I don't know if the evaporative emissions canister purge valve is pcm controlled ( probably is ) on your model year but if you still got the scan tool , see if if can get live data on its activity and the live stream or cross counts on the upstream O2 to see if it's in fact switching rich/lean or hanging up , necessitating replacement. Seems Thera more chasing vacuum to follow . Was hoping you wouldn't have a purge / evap problem but they're somewhat commonplace .

Greg, I still have the scanner until Monday when he needs it back. I did see where I can switch it to a data streaming and where the indicators for both O2 sensors are. I'll write down what the O2 sensors report at idle and at highway speeds. Should I warm the jeep up first like I was doing previously before trying to data log it?

 

[greg92jeepxj]

Well yes but take a look at some open loop data such as the coolant temp versus closed loop for comparison to ensure the CTS is working right. Open loop data is important verses closed loop to ensure sensors are in range by comparison but the closed loop data is what you'll want to work with since an engine is only in open loop when engines cold or at wot ( wide open throttle).
Were also interested in evap if that data is available , that's helpful. Basically , have some fun going through the menu and obtain all that will be of value with regards to emissions , injection and ignition systems . Better to have too much data you won't need than to give back the scan tool and need it again. Best of luck and looking forward to your readings. Post when you can . Thanks , Greg
P.S. - we thank you for sharing this with us since this info is always useful to anyone who may have this problem in the future. Thanks again.

 

[JPNinPA]

Update: Last night I was able to borrow my buddies scanner. When I hooked it up, there were 2 stored codes in the system. (1) incorrect purge flow (2) Misfire on cylinder 3. I cleared the DTC figuring these may have been stored prior to me changing the purge solenoid and the cap, wires, rotor, plugs. After clearing the DTCs, I proceeded to Force Flash the PCM according to the instructions found on the forum. This morning when I started the Jeep to go to work it stip and sputter like it has been (did not let the Jeep idle like the previous mornings). It seems the issue is caused from cold start-up without letting the Jeep warm up before moving. My next thoughts are to check for vacuum leaks and possibly change out the updtream O2 sensor.... Thoughts???

Agree

 

[Bond--007]

Ok, so I was able to do a little data logging on the ride home tonight. It appears both O2 sensors are working properly. While at idle and on the interstate, both sensors were fluxuating between 0.100 - 0.900. From what I could find on a post for O2 testing, these are standard to show the O2 sensors are communicating with the PCM for fuel/air mixture. This leads me to believe the issue causing the sputter is either vacuum related or an exhaust leak (just found out the manifold gasket is bad). Uncovering more and more issues while tracking one down.......

 

[greg92jeepxj]

That's good news that the oxygen sensors are working well and in range which shows the PCM is responding and switching to proper reading of rich and lean. A leaking exhaust will,introduce unmetered air that an O2 sensor may pick up which will no doubt as you know cause the rough idle , stumble and poor acceleration and general loss of power. But yeah , you'll,want to find any more vacuum leaks IF they exist. Still hoping your EVAP system has no issues ? The scan tool is a blessing and really helpful.

 

[Bond--007]

I really should get one instead of borrowing it (damn truck went down tonight, #8 COP took a dump. Irony i still had the scanner....). As for the EVAP, still holding and no pending code. This again leads me to believe it was stored in there before I changed the solenoid out. The #3 misfire hasn't come back either. Again could have been before the plug, wire, rotor, cap change