I have a 1970 Toyota Landcruiser FJ40 that I have been rebuilding for the past year. I have a SBC 350 TBI in it w/ a 700R4 tranny. I have all new painless wiring harnesses (chassis and TBI) and have been working on getting the engine to run smooth but am stuck. I have bought a ALDL cable and have WinALDL hooked up to my laptop and have been trying to figure out why it is running SO rich and rough. I've been reading on this site trying to see what I need to do but have run into a wall. I've replaced the TPS which was bad, replaced my injectors w/ new ones for my motor (Throttle body was out of a 5.0 Chevy Camaro) and replaced them w/ injectors for a 1988 Chevy Suburban 5.7L. I have a new IAC, new MAP, new O2 sensor, new wires, plugs, rotor, cap, dizzy. I do not have any EGR stuff hooked up as I do not have any of the components. My ECM is used and out of a 1988 Chevy Suburban 5.7L (7747). I have been trying to troubleshoot this on the IH8MUD.com forums but there is not as much knowledge there as here on Chevy TBI stuff. I have a fuel pressure gauge on the intake line right before it goes into the throttle body and my pressure reads as the needle bounces back and forth between 11.5 and 13psi.

I pulled my plugs the other day (which were new when I put them in) and they are coated in soot and black. My exhaust has a rich, gassy smell, and has black puffs that come out when it is trying to idle. Once I give it gas it runs better and it seems like once it warms up it idles better also.

Here is a link to my google docs spreadsheet log from WinALDL. If anyone can take a look at it and tell me if they see something that is way off I would REALLY appreciate it. The only error code I got during this run was a error 45 ( Rich O2).

http://spreadsheets.google.com/ccc?k...tY0tWcVE&hl=en

Thanks a bunch,
Nick

 

Anyone?

 

Your log looks pretty jacked!
- First thing I notice is that your MAP readings are very high (low vacume) at idle - they should be in the 35 - 45 Kpa range at idle.
- Also your TPS sensor readings are odd. I do not know what setting you have them shoping (volts or %) abut it should not have negative values. Idle TPS should be around .55volts.
*Make sure you set your idle speed and TPS correctly - unplug spark controll and set IAC and set idle speed (look up procedure here).
- Have you set yout timing correctly?
- Your fuel pressure should not be swinging by 1.5psi. It should be fairly steady.

 

I bought a new TPS and installed it and clocked it, it may have slipped. I had it set at .60v at idle.

I had set the idle speed by unpluging the spark control and going through the IAC reset procedure.

My timing is what has me concerned. My motor when I bought it did not come w/ any kind of timing tab. I installed one the other day and bought a timing light to see where my base timing was. I also reset my #1 cylinder to TDC. As I attemped to adjust my distributor (after setting at TDC) I had to rotate my dizzy counter clockwise a pretty good ways for the engine to begin to run decent. As I did this my timing mark on my balancer was moving away from my timing mark I had installed on the timing cover. It was so far off the mark I could barely see where my mark was on my balancer.

Can timing make your enigine run rough?

Do you think I need to rebuild my fuel pressure regulator in my throttle body?

Nick

 

Nick,
Inaccurate timing can/will certainly make your engine run rough and could potentially destroy your motor. I would recommend that you identify TDC on the compression stroke for cylinder #1 first and foremost. Then set your timing mark to the 0degree mark on your Harmonic Balancer. Then set your timing to 0 w/ the spark control unplugged.

If you do not have any history on the TBI unit, then it may be a good idea to rebuild the pressure regulator while giving the unit a good cleaning. It is cheap insurance.

 

Here is what I did to find TDC, tell me if this is right or I missed something.

First I disconnected my coil, removed my dizzy, and removed the #1 spark plug. I put my thumb over the #1 spark plug hole and slowly cranked the motor until I felt air exiting the hole (air pushed my thumb off of hole due to compression in #1 cylinder). I then used a dial caliper and slowly turned the flywheel (by hand) until my caliper was at the lowest point (highest point of the piston) which then gave me TDC. I then reinstalled my dizzy w/ the rotor pointing at the #1 cylinder and used that point as the #1 plug wire and then labeled the rest accordingly. (I had to use a long screwdriver to turn/adjust the oil pump post to get my rotor to line up w/ the #1 cylinder). I then reinstalled my #1 plug and wire.

From here, can I remove / loosen my bolt on my harmonic balancer and relalighn it w/ my new timing mark that I installed on my timing cover and then just retighten it?

From here I would unplug my spark control and adjust my timing to 0.

I do not have any history on my throttle body as I bought it used off of ebay. I have replaced the IAC, TPS, and injectors on it, but not the pressure regulator. Is it best to buy a pressure regulator rebuild kit from autozone/orielly/napa to replace it? As far as cleaning it, should I just hose it down w/ throttle body cleaner and call it good. It does not appear to be dirty.

Thanks,
Nick

 

Your ballancer should be on a woodruff key that only lets it go on at one exact point. You should not be able to just loosen the bolt and realign it. What you should be able to do is, with the motor at TDC, move the tab until it lines up with the ballancer. It is possible that your ballancer will twist and move under load w/o a woodruff key.

Regarding the TDC, it sounds like your method will work. You do not need to point the rotor at the #1 cylinder, just make sure that the rotor lines up with the #1 spark plug wire.

good luck,

 

So i took my landcruiser to a local mechanic and he set the timing to TDC. He told me he could only get about 6-7 inches of vacuum at idle. He said he added vacuum to it at idle and it smoothed out. At 1100 RPM and up the idle smoothes out and is not rough. I had a mild RV CAM in it and he says that my cam will not run w/ the TBI so I have 2 options, (1) remove my TBI and install a carb or (2) install another cam. This just doesn't seem right. Can anyone give me some other insight?

 

Ya, lets slam the brakes on that mechanic.

Nich your procedure sounded right.

As Keith said the balancer cannot rotate on the crankshaft.
The balancer outer ring can shift .. that's no good, garbage.

At TDC your timing mark HAS to BE at 0* on the tab,
given that the tab and balancer were intended for one-another.

Wrong tab for balancer?

 

The low vacuum is caused by the poor idle, which is probably caused by your rich mixture. Unfortunately on your speed density system, vacuum(MAP voltage) directly affects fuel mixture, exacerbating the rich condition. I would not rush to condemn the cam as I have installed mild cams in TBI motors a several times, with no programming mods.

I will ask though what cam specs you have and is it hyd roller or flat tappet.

 

Sorry it has taken me so long to post back up here, went on vacation. I agree that my issue is not my cam but more so timing, fuel mixture, and vacuum caused by the before mentioned. I do not have the specs on the cam as the previous owner was the one that had the cam installed into this freshly rebuilt 350. All he told me was that it was a "mild RV cam". I do believe it is flat tappet. I think I need to address the balancer first. I was told I have an older balancer on the motor (balancer timing mark at 12 oclock vs. a newer style balancer at 2 oclock). I installed a new style timing cover mark which lines up at the 2 oclock area. I guess I need to buy a newer style balancer that will make everything line up (say off of 1989 Chevy 350 TBI). Once I do this I should be able to get my timing where I know it should be. Then I can address my other problems. Does this sound right?

Nick

 

I think your headed the right direction.

 

Hi Nick, sorry for the hijack but post if you find your solution as I'm having the exact same issues and tried everything you have and then some. 4 different ECMs (7747). New everything, injectors, FPR, and every sensor you can think of. We are stumped as well. Computers are stock for 89 5.7L. Fuel pressure steady at 11psi. Stock except EGR setup removed.

Mine - Fresh 350 GM crate engine (290hp version) installed TBI from 89 5.7L truck and installed into a 87 Monte Carlo. Runs rich and hunts at idle. I can only get it to run with about 15~20 deg of advance, probably due to to much fuelling? For a time we thought we had the wrong damper but apparently the 6.1" diameter is the one GM lists for my application along with the timing pointer they gave us.

I'm making a ALDL cable today so hopefully we can data log some in the next few days.

Anyone have any thoughts????? Sorry I'll start a new thread is need be.

Cheers.
Chris