Acceleration Problems

[PhxExplorer]

I erroneously posted this in General Explorations so I'm moving it here.
Every time I do a modification on my explorer and disconnect the battery for 15 to 20 minutes and then reconnect. The trucks accelaration is awesome for about 30 miles, but then it goes back to the way it was before. What I mean by this is I really have to get on the pedal to get it to accelerate. I have replaced the fuel pressure regulator, fuel filter, PCV valve, spark plugs and wires, air filter, and transmission. The oldest of these mods is the air filter (2 months old). Could this be the O2 sensor since it is about the only thing I haven't replaced. I also have the notorious ticking in the engine at start up until I reach operating temp then it goes away. BTW I have cleaned the MAS 3 times (most recent being a week ago) and cleaned the throttle body about two weeks ago. I'm also only getting about 10 mpg in the city but just one month ago I was getting about 18 to 20 mpg on a trip to Denver. This was before the new tranny, throttle body cleaning, PCV valve, and Bosche +4 plugs.
P.S. I almost forgot, I am losing about 1 quart of oil every 1000 miles but I can't find the leak. Not on the plugs,not in the coolant. I switched to full synthetic when I bought the truck (121K and now have 124,500miles). Sorry this is so long but I wanted to make sure you guys had all the facts.
Please help, I'm really running out of options. Thanks in advance.

 

[Explorer91]

My Explorer act the exact same as your. I also noticed that the temperature gauge point at half way. Normally the gauge always below 1/4. We need help! Any advice from other 91 Explorer owners?

 

[SteveVB]

O2 is a good guess- and most likely but could be other. Engine coolant sender, vac leak, do you have any codes.
Running around town and driving on the Hway to Denver are quite different so the milage may not be off as much as you think. Just a thought.

Oil:Check the intake manifold. Check the gasket at the rear they have a tendency to leak and the oil ends up on the bell housing and tranny. Also the lower intake manifold bolts loose their torque with the heating-cooling cycles so you may want to check them.

Ticking: check what filter you use- search the site, Fram has a poor drainback valve.

91- your coolant gauge should read the halfway point . The t-stat may be sticking open and letting the engine run cool.

Hope that helps some.

 

[Xplor]

PhxExplorer, the same happened for me when I used to have my '92. I was using Mobil 1 and I would had to add a quart right at 2,000 between oil changes. It started when it had 95k miles and traded it in at 120k miles. Do you had a rattling/pinging noise while driving at highway speeds or accelerating?...I have. I was using premium gas, tune-up, fuel system flushed. etc. And did not help. There was a slight leak from the rear manifold ( I think ), but am leaning on the lifters too.

 

[Josh Adams]

Had the same problem myself

I had the same problem, and I took the same route that you
did, but I did not change the tranny out. The problem ended
up being the mass air flow sensor. I did not clean it, I
went to the parts store and got a brand new one. It wasn't
sending a good signal to the computer, so it was running
lean, and the temp. was up a little. So maybe give this a
try, it may not be the answer, but if you have alot of miles
on your truck, it maybe time for a new one.

 

[FMNavajo]

PhxExplorer,
I think SteveVB has pointed you to the problem area. I have a 92' and when I got it's mpg was around 10-12 city and 13-14 hwy. Everytime I went on a trip it would ping at hwy speeds and going up hill on a steady acceleration. It was also burning oil like you described.

Solution that worked for me,
I spent about $200.00 and purchased the intake manifold gasket kit, valve cover kit, fuel pressure reg., O2 sensor and all necessary items to complete the project. I then spent a rainy weekend in my garage and went at it. Since then I've been monitoring the mpg and it's up to 17-19 city, and around 20-22 hwy at 65mph.

I'm also running 87 octane fuel, prices in CA are crazy.

Hope this helps,
FM

[Edited by FMNavajo on 08-15-2000 at 12:33 PM]

 

[skender]

Same problem

I had the same problem but on my saturn. Turned out to be a leaky intake manifold gasket and a leaky fuel pressure regulator. Fuel was leaking and mixing with the oil making the oil thinner and more prone to burning up.

 

[skender]

word on premium fuel

From what I understand most amercan cars were designed for use with regular 87 octane fuel. The ECU's preprogrammed fuel curves are mapped out around the cheap stuff. Putting in premium fuel is really just a waste. What ends up happening is not all your fuel gets burned and what's left mixes with your oil. In the end you have a light wallet and nasty black goo for oil. Unless you have a chip upgrade with fuel curves for it premium is a waste.

 

[PhxExplorer]

Well thanks for all the tips guy's. Man I love this sight. Sounds to me like the general consensus is to replace my intake manifold gaskets and valve cover gaskets. Never done it before, but I'm always looking for a new challenge. There's something so satisfying about undertaking a new project on your truck, getting it finished, and having it solve a problem. And you didn't even have to pay a mechanic. See my girlfriend doesn't understand this. She thinks it is a piece of junk since I'm always in the garage "under the hood". But I then start throwing #'s for repair costs at her and it quiets her down for a while (til it's time to take out the garbage or help clean up the kitchen). She has a 93' 4-Runner and takes it into the dealer for everything (oil change, tune-up, brakes, etc.) she won't let me touch anything on the engine "YET".

BTW I'm also going to change the oil and filter this weekend with mobil 1 synthetic and just stick with that brand. Once again thanks for the tips. Is there any tricks or possible problems I may encounter getting to the intake manifold gaskets?

 

[FMNavajo]

Have a good manual, I have a Haynes and it outlines each step to this procedure.

I think the bigest problem was keeping the AC lines out of the way while removing and installing the parts. Another item is to clean everything spotless prior to reinstalling. Use a good intake or carb cleaner and have a few small soft wire brushes available to speed up the cleaning process.

Something you could try to avoid problems with the better half is just re-torque the lower intake manifold prior to changing it out. After you do this, run it for a week and see if it made a difference in power and oil comsumption.

One thing that made me decide to take this on was the #5 spark plug had a considerable amount of carbon built up on it as compared to the others. That's were the gasket seems to leak first.

Good luck,
FM

 

[SteveVB]

FM has a good Idea about retorquing the manifold bolts first to see if that helps.
I would recommend that you get a service manual if you dont have one. If you have never replaced the intake before I would read through the process to familiarize yourself with it before you start. The factory has one for about a 100, but the $15 Chiltons, or Haynes are good also. They all have the info you will need to remove and replace the lower intake manifold.

Have fun!

 

[PhxExplorer]

All right, I feel really stupid. I was looking in my hood compartment last night and happened to put a little weight on the air intake hose that attaches to the throttle body, and what do you know, it's not connected to the throttle body, just kinda hangin' there. So I reconnect it, disconnect the battery for 20 minutes, and then take it for a drive. That seemed to be a majority of the problem, but it still doesn't respond like I think it should. So I'm still going to do the following: 1.retorque the lower intake manifold bolts and clean everything I can get to 2.change oil and filter 3.change the t-stat to see if it helps with the mpg and rough idle 4.replace the O2 sensor and 5.replace the MAS. After these are done I should just about have a new truck!!! I'm going to start on the list on Sat. and I will let you guys know how it turns out. Thanks for the advice. BTW I'm still looking for someone to help me replace my radius arm and crosmember. (hint!hint!)

 

[leebo]

It's always the simple answers that are the hardest to figure out isn't it. I think that we have all been there at one time or another.

Dead Link Removed

 

[PhxExplorer]

Well, I changed the oil and filter Friday with a Mobil 1 filter and I went with Castrol Semi Synthetic oil and my ticking noise is gone!!! Thanks for the tip on the oil filter. I am still going to try to retorque the intake manifold bolts this week and clean everything out. Something else, my mpg has gone way up since I changed the oil, those Fram filters must really be junk!! I am going to wait on the MAS til I have everything else on my list done since this is the most expensive part. I'll keep you giuys posted.