Decided to start a new thread on this since the headers don't seem to be a problem.

I ran some injector cleaner through a tank last during the week to no avail. The fuel pump and filter are new.

Most of the time when I take off from a stop it hesitates a second until I give it enough gas, then it surges forward. It also sounds like the throttle or fuel delivery fluctuates slightly while cruising at a constant speed.

The fuel injectors are the only thing I used that came with the 3.4 (126k miles, found in junkyard)

I tried testing the tps a long time ago, and it seemed to have a tiny dead spot, but I wasn't having any problems with it, so I never replaced it.

Tomorrow I'll take it to Cut-rate, they said they'll do a diagnostic check for free. Maybe find out things I can't when I do the jumper wire check.

I'll also check for fuel leaks, re-torque the headers, and test the fuel pressure after I turn it off.

Any other suggestions?

 

I was having a simular issue with mines after my swap. I replaced the o rings on the injectors and also the fuel lines. Seems to have fixed my issues but not sure it will help you. If your not smelling fuel under the hood I don't know. It might be worth a try. Good Luck!

 

lil mor einfo needed.
are u using the a maf or speed density computer,or did u swap over the 3.4 computer.
have u done a compression test/leakdown test,engine run hot or cold?
motor always ran liek this or just recently and if recently what changes have u made to the car/engine

 

It's all 89 2.8 computer stuff. MAF. I don't think I smell fuel, but I'll be checking tomorrow. Did a compression check when I installed the new timing chain (the new one replacing the other new one that broke) The compression was pretty good. Probably better now that it's been ran and all the extra gas in the rings has been replaced with oil. Last week I could smell exhaust everytime I started it, but that seems to have gone away.

The only change recently was the 3.4 installation. I'm too tired at he moment to typ any more. Will return tomorrow with results of checking.

 

The stumble off the line can be the TPS.

I'm still wondering if your injectors are leaking.

You say it serges while driving? That can be a flattened cam, 02 sensor, or vac leak.

 

Had a scanner tool hooked up today at cut-rate. No codes to be found, but there were two things that were reading lean. I'd have to get it hooked up again and write down exactly what it said.

Dumped in 2 bottles of Lucas injector cleaner.

Got home, jacked up car, turned key on, and sniffed/looked everywhere from the fuel tank to the injectors for a fuel leak. found none.

Hooked up the pressure gauge, went to 40 while priming, dropped to 35 when it shut off, and took about 10 seconds to drop to around 25. 30 seconds to reach 10 or so. Is this too fast? If so, all I can think of is an injector being stuck open or leaking, but wouldn't that cause a rich reading?

Hoses going to fuel regulator had no fuel in them and didn't smell like fuel either.

Found a smear half dried coolant at the rear-right head gasket area. looks like it had been running down the side of the block. My coolant was low in the tank too. I bet when I start it in the morning when the block is cold I"ll see it run out until it warms up. (Seen it before on an L6 generator engine) I wondered if I should have hot-torqued those bolts. We went around them about 7 times with the torque wrench.

I'm thinking during the week I might order those injectors, then pull the intake next weekend and put them in. Found re-manufactured sets for $240-ish. I also kinda screwed up when I didn't clean the injector holes thinking the 3.4 injector o-rings would seat down in as far as the 2.8's did. I doubt how well some of them may be sealed.

Maybe I should buy that truck I just fell in love with on autotrader so I'll have something to drive while I rebuild my rebuilt engine.

(edit)or maybe it's that right-rear head sensor that's leaking.

 

that fuel pressure is dropping too damn fast, you have a leak somewhere. If not at teh engien, then trace back to the fuel pump. My feed line had a small pin hole init that I discovered while putting the 3.4 in. It was very small, and up against the frame rail. I'd hold off spending more $$$ on ijectors, esp if they aren't the problem.

 

Projects right, that fuel pressure drop is too soon, to fast. Either an injector is sticking open, or the sending unit in the tank is bad. So every time you turn the car off its dumping extra gas in the engine to just evaporate. Part, but not all of your mpg drop.

Also, if one is sticking open, its not pulse-ating and is spraying to much gas. LEt alone, what kinda spray pattern does it have now? May not be atomizing the gas properly.

Coolent leak on the head is not good. If you have a compression tester, I would test the engine and see if your not getting full seal on that head loosing compression.

 

are u blowing out white smoke? cause u said u had coolant on the block and if ur blowing out white smoke well then u'll have urself a blown head gasket.

 

no smoke coming out. I was going to see if it was leaking coolant this morning, but I forgot when I left my friends house. I want to wait for it to cool down and then I'll see if it's coming from that sensor or the head gasket.

If there's a leak in a line somewhere, it's going to be a pain to find. When I looked at the line yesterday I couldn't see or smell fuel anywhere, so I'll have to look closer I guess.

The fuel pump is also louder while driving. I don't know if my old one was just quieter and the new one is louder, or if it's working harder because of a leak. I don't remember the old pump being loud though the short time it was feeding the 3.4 before it was replaced. I also didn't really get a good idea of the fuel usage though either during that short time.

Kinda makes me think it's leaking up above the fuel tank where I can't see it. (sigh)

 

Coolant was coming from the temp-sensor on back corner of head. Tightened it. I guess as it leaked down it spread along the edge of the gasket. I hope.

Can't find, see, or smell any fuel leaking anywhere from the fuel pump to the injectors. I guess it's either draining back through the pump (which is new and if it is leaking back into the tank, I can't quite see how it would destroy my mileage that much) or the injectors are messed up.

All 6 spark plugs are blacker than they should be. Unless that's from when the o2 was bad. I cleaned them up and will see what they look like next weekend.

If the TPS is bad, then I don't see why it wasn't really giving me trouble with the 2.8, but I can replace it anyway I suppose. I'm really leaning towards replacing the injectors.

Also, the base timing for the 3.4 is 10* just like the 2.8 right?

 

hey if u want i have a few sets of injectors laying around( have to check and see what sizes though) i think there all 19# or bigger,though 19's would be fine on a 3.4.if ya want a set let me know and ill check.sell them cheap

 

yes, tps can go go all screwy on ya, it did on mine.

and there's nothing in the holy book haynes on timing, as the regular have no dizzy & timing controlled by the comp, but I don't see why the timing would be diff from what the 2.8/3.1 is.

side note: most peeps adjusting the timing bump it up to 12*

 

Timing is based off the ecm, not the block. 10 is correct.

 

I think tomorrow I'll check to see if it's entering closed loop mode. I did some searching and found out about checking that.

 

I'll think about it. There's a set I might be able to get at the junkyard off an 80k mile car, and maybe have them rebuilt. Or get those re-manufactured ones at the parts store in town.
I like to have new or at least re-manufactured, but I'll see.

 

a 3.4 will run off 19's, and run better up top. However, down low it will load up bad.

 

dale his wont since hes using the 89 maf setup,if u read my other thread i have a bone stock firebird running on 24# injectors and it runs perfect.it dosent load up at all,and deff runs better uptop.it will run a lil rich during cold startup though ,but not rich enough to hurt anything.i posted actual afr numbers for diff driving conditions in the other post

 

Well I tried checking for closed loop mode, but the test didn't work. I may see if those injectors are still at the junkyard, or order the re-man set in the next few days.

The fact I'm losing fuel pressure, o2 is setting off a code again (even if it is lean), it runs bad, and the plugs are turning black, all kinda makes me think my injectors (or a couple) are leaking or stuck or something.

ACtually all 6 plugs were black, and unless all 6 plugs are leaking, then there's probably something else screwy too.

*edit, although I guess a lean o2 and running rich is a major sign I have an exhaust leak. The gaskets are all new and I can't hear a leak, but I'll look closer I guess.

a friend of mine says he knows someone who has an injector flow tester setup. I'm going to see about using that.

edit again* accel injectors for $194 in summit. I might just go that route.

 

Dont know what post your talking about. But then I have also not worked on a maf thirdgen to know how it all works.