Low manifold pressure?

[sleepyalero]

Twice now, once i went to the track. The ses light came on it said low man press. Replaced map. All was good. Just got light again today, low man press. What can cause this? Ive read worn piston rings, valve guides, vac leaks..... Any help?

[Starglow]

A 3500 swap would fix that!! :p

[sleepyalero]

Thats the plan next year with a turbo. ;)

[Ecotecalero02]

Have you done a compression test yet

[sleepyalero]

Not yet, i think i have one just gotta find it.

[Ecotecalero02]

Ok that should tell you a lot if there is low compression in one cylinder put a small bit of oil in that cylinder if it improves its got bad rings if not its a gasket or head issue

[sleepyalero]

Okay thanks.

[Ecotecalero02]

No problem I figured it might help you in troubleshooting

[xXManwhoreXx]

Ok that should tell you a lot if there is low compression in one cylinder put a small bit of oil in that cylinder if it improves its got bad rings if not its a gasket or head issue

This does work well!

[sleepyalero]

Okay, i did a compression test on all cylinders, they were all at 180 or a little over. So that checks out ok.

I pulled the fuel pump fuse and IGN MOD fuse for the test so the car would only crank and not try sparking/getting fuel.

Edit: car is running fine, i unplugged battery for about 15 min to clear codes and i started the car the ses light is on. Just replaced map and tps because i got codes for them today. Hopefully after a few start ups it realizes that the problem (should be) fixed.

If not ill have to get it scanned again tomorrow.

[sleepyalero]

Okay another update. If i didnt mention before... I replaced the tps and map sensor again because the ses light tripped. Replaced both and did compression test, all at or slightly above 180. Started car up once all was done. Ses light was still on, unplugged battery for a bit, started it again. Still on. After a few more starts, it was gone. So guess we will find out what happens.

Also, notice i have a auto trans fuse. Pulled that tonight to see if it will help with my idle issue. Doubt it could but worth a shot. I figure i dont have an auto anymore why should i need it. Wont know till tomorrow if the car runs better without it, its raining and the car doesnt get driven in rain. :lol: so shes stayin in the garage.

[Ecotecalero02]

Hope it goes well for ya

[sleepyalero]

Thanks man

[jawa]

better take dem wipers off then cuz you know it dosent see water from the sky heaven forbid, oh you can get away with running race slicks year around too ,

[jawa]

put a lx9 in it and call it a day

[sleepyalero]

Hahaha it will have a 3500 turbo build startingg next year buddy.

[jawa]

how about starting now

[sleepyalero]

Need money.


Start donating.

[AleroB888]

What numerical code does it set? example: P0300 = misfire

[sleepyalero]

I didnt get th code from the guys at autozone. :(

So far after changing the sensors and doing a comp test and few other small things the car seems pretty good atm. If it pops back up ill have to get the code.

[02AleroGLS]

Does anyone know what would cause a rough idle on a 3400? It runs fine other then that but it was throwing a code for bank 1 lean, and purge control valve. I've changed the FPR, IACV, spark plug wires (Borg warner brand), changed ignition coils, ran B12 through it, llugs are AC DELCO IRIDIUM'S with less then 40, 000 miles on them. I've checked for vacuum leaks the best I can but haven't heard or seen or felt any. And I replaced the MAF. I'm at a loss for ideas.. It's suckjng gas bad too..

[sleepyalero]

Replace what the computer tells you is bad first, then go from there.

[a.graham52]

Does anyone know what would cause a rough idle on a 3400? It runs fine other then that but it was throwing a code for bank 1 lean, and purge control valve. I've changed the FPR, IACV, spark plug wires (Borg warner brand), changed ignition coils, ran B12 through it, llugs are AC DELCO IRIDIUM'S with less then 40, 000 miles on them. I've checked for vacuum leaks the best I can but haven't heard or seen or felt any. And I replaced the MAF. I'm at a loss for ideas.. It's suckjng gas bad too..

way to thread jack...

just an fyi, the 3400 does not have a "true" bank1 (lean/rich condition) because it cannot tell the difference between bank 1 and bank 2 (only has one up-stream 02 sensor. unlike a v8 truck for instance which has an upsteam for both left and right banks.

btw how did you check for intake leaks?

try this, unplug the MAF sensor and clear the codes (unhooking the battery or w.e u choose to do) and then see if the car runs better with the maf unplugged. this works best if you can view fuel trims. if the if the car runs much better you probabaly have a vac leak (long fuel trims come close to zeroing out rather then be high positives). lets say you unplug the maf, cleare codes and still runs like poo... then you probably have another issue like fuel delivery or bad 02 sensor.

mind you this works BEST when you can see live fuel trim data, can erase and "relearn" fuel trims (unhooking battery for 1o minutes should do the same) and can also test at a steady 45-60mph to get a good idea what your cruise long term trims are.

[sleepyalero]

Its okay, i really dont have much left to ask. So far my car seems okay. We'll find out soon enough.

But if i have more problems ill be back.