258 doesn't pull past 3000RPM. Why? - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 06-11-2000, 10:51 PM Thread Starter
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258 doesn\'t pull past 3000RPM. Why?

is my tach off by 1500RPM? my redline is SUPPOSED to be 4500 but I've never come close. it feels like there is no power past 3000, except in 3rd someimes for some reason. It feels like it wants to blow at 3500. Is this a tach problem or an ignition. I havent followed the TeamRush stuff too much. Is it written up somewhere like the chevy HEI swap? I don't want to do the HEI cus it bypasses the computer.

'89 YJ 4.2L, AX-15, Flowmaster, Euro Taillights

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post #2 of (permalink) Old 06-12-2000, 12:03 AM
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Re: 258 doesn\'t pull past 3000RPM. Why?

Make sure your distributor advance is working. Pull the line off of the distributor and rev the engine. You should feel the vacuum get stronger as you go up in rpms. Then check your timing to make sure you are as close as possible to what it is supposed to be. I think, for mine at least, it should be about 8degrees btdc. Not 100% sure on that one. You should try the TR upgrade regardless due to it's simplicity, price, and the difference you can feel.
Mine wouldn't go above 3000 for a while until I realized the advance wasn't hooked up right. Now it pulls to around 4000 nicely, even thought you should never need to go that high with a 258.
Hope this helps some.

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post #3 of (permalink) Old 06-12-2000, 02:10 AM
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Re: 258 doesn\'t pull past 3000RPM. Why?

My '84 CJ7 with the 258 I6 never would really get past 3000 RPM either. It just seemed to hit a wall at 3000 RPM. I did the TeamRush ignition upgrade and now I have no problem blowing by 3000 RPM. I suggest the upgrade - its cheap, easy, and effective. Plus, it makes driving a lot more fun.

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post #4 of (permalink) Old 06-12-2000, 04:16 PM
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Re: 258 doesn\'t pull past 3000RPM. Why?

*Some* Reasons for not getting past 3,000 RPM...

1. You didn't do the 'Nutter' bypass... (no flames please for saying 'Nutter')
(two wires, easy to do)

2. You are getting so much cross fire in the distributor cap it can't rev any higher.
(Get better rotor, Go to wider cap with brass terminals)

3. The advance has come in, and you are firing the wrong terminals in the cap.
(go to wider cap with brass terminals, wider cap spreads the terminals out)

4. Your coil is laying down on the job.
(Get a 'Hotter' coil, like the Ford TFI coil)

5. You plug wires have degraded to the point of not being able to do the job.
(Get low resistance, high efficiency plug wires)

6. Your ignition module may be lying down on the job.
(about $20 for a new module. Get the 'Blue Grommet' module)

7. One or more of about a dozen connectors may be fouled and not making good connection.
(Open and clean all connectors involved with the ignition system)

8. It may be a problem with the Tach. It's rare, but bad tachs have been know to work like rev limiters, or kill the ignition all thogether.
(There is a way to jump the tach to see if that's it.)

9. It may be a problem with the Module ground. This is pretty common.
(It takes three feet of 12 ro 16 ga. wire and ten minutes to fix)

10. May be 'Mystery' problem...
(If that's the case, we'll help you find that problem and kill it.)

9 chances out of 10 the large cap/ TFI igniton upgrade that is being called the 'TeamRush' upgrade will fix your problems.
Just about anyone can do it, and it's all parts you change in a good tune up anyway...
If you are interested, there are several here that can help, including me.

Good luck, Aaron.

"I Have The Body Of A God... Buddha"
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post #5 of (permalink) Old 06-12-2000, 04:28 PM
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Re: 258 doesn\'t pull past 3000RPM. Why?

My Jeep used to do the same thing, after 3 grand it would just twiddle its thumbs. A while ago I completely drained the transfer case and transmission and replaced the fluid. It now hits about 4200 before it loses power. This is all with no Ignition mods, on a bone stock carb too. Changing the tranny fluid seems to do wonders for most cars (my friend eliminated a particularly nasty 2nd gear grind on his Eclipse GST with a tranny fluid change), so that is what I would reccomend trying first. Also, dont go for the cheap tranny fluid, you only change it every once in a while. It cant hurt, even if it doesnt help, at least you know your tranny will be up to the task when you finally do hit the 4500 RPM "Holy Grail". Good luck!

89YJ 4.2 5"lft 33"Firehawk ATX
post #6 of (permalink) Old 06-12-2000, 08:35 PM
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Re: 258 doesn\'t pull past 3000RPM. Why?

How about a simpler answer..... YJ tachs are notorius for not being all that accurate! I thought mine was not reving past 3000, although it sounded like it was.I hooked up an auxilary tach and found it was revving up just fine! Just something easy to check out first.

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