im having trouble with the throttle
Senior Member
Joined: Jan 2011
Posts: 801
Likes: 1
From: N. IL
Year: 2000
Model: Cherokee
Engine: 4.0
I went back through this thread and the OP never said he wasn't having starting problems. So the suggestions to check the battery were not incorrect. He did say he has a leaky injector and that could cause the problem and should be fixed.
Member
Joined: Sep 2010
Posts: 112
Likes: 0
From: St Louis Park, MN
Year: 1998
Model: Cherokee
Engine: 4.0L
Well, the 71 Waggy with a Buick 350 is a simple motor, also, back in 71 Alternators didn't make a ton of amperage so a bad battery cripples the ignition because I would assume you were running HEI, so yeah that would do it. And yeah, I normaly ignore people but my curiousity peaked when there was a solution given that didn't add up to what I was thinking so I asked then ended up being told I was wrong.
Last edited by textherex; Feb 1, 2011 at 09:34 AM.
Registered Users
Joined: Sep 2010
Posts: 1,354
Likes: 1
From: Elkhart I.N.
Year: 1987
Model: Cherokee
Engine: 4.7L
I know the op and his jeep well and it has no problem starting, he is fairly sure that his problem is injector related but I have seen how the jeep is acting first hand and I would put money on it not being a problem with the fuel delivery system, his tps is fairly new, I'm starting to think he may have a wiring problem any ideas?
Member
Joined: Sep 2010
Posts: 112
Likes: 0
From: St Louis Park, MN
Year: 1998
Model: Cherokee
Engine: 4.0L
It could be wiring, in electrical things get goofy. A leaking injector will not cause his issue. It very well could be the PCM, I think I said it before they are known to have a screw corrode in them and cause numerous drivability problems.
CF Veteran
Joined: Jun 2009
Posts: 5,383
Likes: 5
Year: 1988 limited
Model: Cherokee
Engine: 4.0 litre
The problem that I am having it is not about someone disagreeing with me. I can handle someone having a different opinion then me with no issue, the issues come when some tells me I am wrong and fails to give proof why. I never said Desk Jockeys don't have the abilty to work on cars, but there is a difference in thinking between someone that works on cars for a living then someone that works on them during the weekend. Also, some cars have fail safes that save the Alternator from being killed when the battery is disconnected, because as I have agreed Running the car without the battery isn't healthy. Also, the one fact that has been over looked and I never said it because as a Tech it is assumed, the Battery is fine, does the Jeep start in the morning? Does it start everytime you get in it? If it does, there is nothing wrong with your Battery. Yes, The TPS is very sensitive to Voltage, but that is the job of a Voltage regulator to control that and not the battery. I was trying very hard to have you understand that the battery isn't the problem, TPS's tend to not throw trouble codes. O2 Sensors throw codes all the time because the EPA dies a little on the inside when one goes bad. A fuel pump is possible but I doubt it since you can keep the Jeep from dieing by pushing the throttle to the floor also on the same note the Fuel line/rail would be ruled out on that, true they can do what is called Vapor lock. When Vapor lock happens you can't save it by hitting fuel throttle. Ignition like the Spark plug, wires, cap/rotor aren't going to care if you are at full throttle or not. Now a coil can do that, they tend to be random and make it hard to Diag at times. The problem you are having is something not easily diag'd without the right tools, run the codes, Jeeps and most cars for that matter can throw codes and never turn on the MIL, or the Check Engine Light. My suggestion is, do the simple stuff, before you spend money on replacing the TPS or IAC, make sure the connections are strong. Make sure they are clean, beware of taking the IAC apart, there is a weak gasket that is easily broken along with it. Also, a word to the wise and as a Tech bringing us something that is Random with no obvious signs can cost you alot of money in Diag hours, unless people at Jeep know a fix for that. Your best bet is go to a Jeep dealer and talk to the parts guys, alot of the parts guys are old techs that have killed their bodys doing full line for 20 years, they might be able to help you out for free, well if they are cool, beware of the 30 year tech/part guy, he cares about nothing just waiting out his time so he can retire and isn't going to help anyone lol. I am sorry for flaming Desk Jockies, just when you have a piece of paper saying you are Ford Certified in Electrical Diag it tends to get under your skin when simple Electrical fuctions in a car are explained and you get told you are wrong and don't know what you are talking about. Btw, just as a sign, I asked twice how the battery could cause that issue after not being showed how the battery itself could cause that issue I got pissed being told I was wrong.
You were wrong when you said that a jeep cherokee with the chrysler SBEC fuel injection can run without a battery. The alternator on a jeep cherokee has a built in voltage regulator that measures the potential difference between the battery + terminal and the stator + output. If this delta is significantly high (dead or no battery) the regulator isolates the rotor windings (fail safe) to protect the diode rectifier bridge from overload. This means no electricity is produced by the alternator.
The only case when a vehicle can run without a battery is with a standard constant charge alternator ( ie Bosh R-L series) that will measure an impedance tending to infinite and give the maximum charge output until the brushes melt (c.ca 15 minutes with a new set of brushes).
These alternators are found on diesels, carburetted and single point injection vehicles pre OBD II, not in a RENIX or SBEC cherokee.
A bad fuel pump will act exactly like the OP stated, run at idle, sputter in acceleration and run fine at WOT, why? Because the maximum fuel request is when we open the throttle, the MAP sensor reads the maximum vacuum possible and regulates the injection opening time to the highest, when the throttle is completely open more air can flow in the manifold and the vacuum reading will be less, therefore less fuel is required.
I suggest he measures the fuel pressure WHEN the engine sputters by connecting a pressure gauge on the rail that can be read while driving.
Member
Joined: Sep 2010
Posts: 112
Likes: 0
From: St Louis Park, MN
Year: 1998
Model: Cherokee
Engine: 4.0L
Sigh, I have done it on my 98, I can't say for anything else. Again, as I said there are built in fail safes to save the alternator beventing the car from running without the battery. I know the consequences to not having a battery, I really don't understand everyones jump to start explaining how this does this or does this. But, you know what I am not even going to bother going any further on that. As for your solution, Fuel pumps can do what you said, just that the OP stated it is just going down the road, not accelerating. But getting the fuel pressure isn't bad idea. Fuel pump is still cheaper then a PCM.
CF Veteran
Joined: Jun 2009
Posts: 5,383
Likes: 5
Year: 1988 limited
Model: Cherokee
Engine: 4.0 litre
Sigh, I have done it on my 98, I can't say for anything else. Again, as I said there are built in fail safes to save the alternator beventing the car from running without the battery. I know the consequences to not having a battery, I really don't understand everyones jump to start explaining how this does this or does this. But, you know what I am not even going to bother going any further on that. As for your solution, Fuel pumps can do what you said, just that the OP stated it is just going down the road, not accelerating. But getting the fuel pressure isn't bad idea. Fuel pump is still cheaper then a PCM.
You can everytime post a video of your 1998 jeep cherokee still running with the battery disconnected.
Member
Joined: Sep 2010
Posts: 112
Likes: 0
From: St Louis Park, MN
Year: 1998
Model: Cherokee
Engine: 4.0L
Alright, stay tuned then and I will rock your world. Also, as far as the fail to show me proof, you are explaining why it is bad to run the car without a battery, not why you can't. But that is fine, at 5pm cst will pull my jeep in the shop, with one person filming me on my iphone, I will pull the battery out of the jeep while it is running then put it back in and it will stay running, or would you like me to use what I did. Pull the battery that is in it without it running, put a different battery in it, start to truck, then remove that battery and put the old battery back in? Just asking so that I can give you the proof you have called me out on.
Member
Joined: Jan 2011
Posts: 163
Likes: 0
From: St. Helens, Or
Year: 1986
Model: Cherokee
Engine: 2.5L
Member
Joined: Jan 2011
Posts: 163
Likes: 0
From: St. Helens, Or
Year: 1986
Model: Cherokee
Engine: 2.5L
I am a man of my word, and I had some down time so I got it done sooner then planed. Here is the link
http://www.youtube.com/watch?v=1obJDuueoh0
Enjoy
http://www.youtube.com/watch?v=1obJDuueoh0
Enjoy
I think he makes a solid point.....
Member
Joined: Jan 2011
Posts: 163
Likes: 0
From: St. Helens, Or
Year: 1986
Model: Cherokee
Engine: 2.5L
He admitted that it isn't a good idea to, he just wanted to make the point it was possible to. In one of his previous posts he said that you'll burn up your alternator if you do that.
CF Veteran
Joined: Jun 2009
Posts: 5,383
Likes: 5
Year: 1988 limited
Model: Cherokee
Engine: 4.0 litre
I am a man of my word, and I had some down time so I got it done sooner then planed. Here is the link
http://www.youtube.com/watch?v=1obJDuueoh0
Enjoy
http://www.youtube.com/watch?v=1obJDuueoh0
Enjoy