Lenbo211

I was thinking the same thing. When I bought it, I bought a pair so going to put another one in line.

I have the dial turned the whole way to get it where it is.

Did this. It definitely runs better now. throttle response in shop that I'd expect. Can set idle up around 1000 rpm no issue. However, when I take it out for a drive, it stumbles when I add throttle under load and takes a second or two to take off. Something else is that when I'm on maintenance throttle going down hill, it is backfiring. (i think backfiring. I have hood off so not entirely sure if it is firing out of the air filter like it did in the shop, or if it is coming out of the exhaust. This is the first time I've driven this car.

Thanks for the answer on resistance. I did a little more looking and realized that infinite resistance = 1 on my meter. Yeah, I did have it on the brake booster earlier and it bumped up to 15 when I hit the throttle. but the point is the thing stumbles when I add throttle so I moved the vacuum gauge so I could get a reading on what the ported vacuum was doing on the throttle body to see if that was normal. Did you watch the video? Maybe it's not clear in the video, but it idles OK, but runs horrible when I add throttle.

OK, I did a full test on the AFM and it all came back correct. Here is a video of the car running. Hopefully the video gives some of you Z Heads an Aha! moment. https://youtu.be/nfUWozhWMzA There are a few things to see so you may want to watch it a few times. Fuel Pressure gauge. Looks like it is working as expected. I have vacuum gauge. It is low at idle, but consistent. It is plugged into the line between the intake and the Distributor/Throttle body. When we add throttle, it drops to zero. Is that normal? idle is around 800 to 900. that is as high as I can get it to go with the idle set screw. The timing light is shown blinking in the background as well. I have it connected to the negative terminal on the coil. Something I saw when I was watching the video is that the light blinking isn't consistent on throttle input and release. might not even be that consistent on idle, but it's hard to tell if that is just the shutter speed difference on the camera. But light goes away when we blip the throttle and let off. that doesn't seem right. It's like the coil stops receiving or sending a signal. Could that be the TPS? I wonder if the TPS isn't telling the computer what to do correctly so the signal from the disti gets lost in transit to the computer or coil? I tested the TPS last week per the FSM. The Idle switch check came back fine and the full switch check came back fine. When I did the Throttle Valve switch insulation check, I didn't fully understand what it meant by "infinite" on the ohmmeter. I'll check that again tomorrow if I can figure out what an "infinite" result would be. One thing I know is this car was parked 10 years ago for a reason that died with the guy who parked it. The cam could be an issue, but it wasn't the reason he parked it so I'm probably chasing what caused him to park it.

Thanks, Great information. I've talked to Bruce at ZTherapy a couple times. $1,400 for a carb conversion so about the same as the Fast EFI. I'd probably rather do Carb, but Bruce is backed up to September with orders. Does anyone have troubles getting the carbs to work well without waiting to warm up? That's the only drawback I've seen on the forums around doing a conversion.

Thanks, Do you think it's an ECU thing that I could fix by swapping from Factory to a MegaSquirt etc?

Any throttle input causes it to stumble and almost die whether it be slow input or fast input. I may not be explaining it well, but it is definitely not normal. trying to give it a little throttle just to let the clutch out and get moving is impossible. I'll try and take some video tomorrow and post it so you can see what it's doing.

In my '78, there is a line that runs from cannister across to the distributor and T's to go to distributor and to the inboard side of the throttle body. Makes sense on the ported vacuum. the fact that the timing advances when I add throttle indicates that the ported vacuum (only having vacuum when rpm goes up as blade opens) is working as it should. A friend suggested it could be Fuel Pressure related and may need to get an aftermarket FPR. I have a new Factory FPR. It shows 33 at idle and jumps to 40 when I blip the throttle. Is that normal? I always thought it should drop when you blip, but not entirely sure on this car. If I need an aftermarket FPR, is there one you'd suggest? This '78 has a very odd shaped FPR compared to other Z's.

Hi All, I did a little searching and while I'm guessing my issue is common, I can't find an existing thread. Our car starts fine regardless of temp outside. But we are having trouble with the throttle response. As in, if we slowly move the throttle, it stumbles but eventually comes up and if we blip the throttle, it almost dies and then runs up after we let off the throttle. For a while we thought it was a vacuum leak because no matter what we did, we couldn't get the idle above 650. Found a leak and fixed it. Can get it to idle at 800 now. Using carb cleaner spray test, there is now no vacuum leak we can find. Now the idle seems fine, but still falls on it's face when we blip the throttle. Big ISKY Cam 718149 (Link Below) so I have about 10 vacuum off the intake at 800 rpm idle. goes up to 15 when I run up the RPM. (To set this at 800 rpm Idle, I had to back the Idle set screw out a decent amount. Further than I figured I would need to) HERE IS MY PRIMARY QUESTION: I checked vacuum at the input to the canister and exit of canister and it shows the same vacuum as at the intake. I checked the vacuum line that T's to the throttle body and distributor. When I pull both of them off and plug one with my thumb, the other has 10 vacuum. When I plug the vacuum line into the throttle body, the line going to the Disti is 0 vacuum. (Is this normal for vacuum loss in throttle body?) I did a mouth test on my disti vacuum pot and it moved the internal advance. Have set the timing at 10 BTDC at 800 idle.(Left the vacuum line on disti. Not sure if this is proper, but when I took it off, it made no difference in how it ran or where the timing mark showed.) And when I run up over 3,000 RPM I see the advance mark go up to about 30 advance. I checked the TPS per FSM and idle position shows correct value and Full Position shows correct value. Still need to test AFM per FSM, but was able to make the rpm change by putting my finger in and changing flap position. Checked the Air Bypass valve. It is open about 1/8th inch when cold and closed at operating temp. My understanding is this is correct. Checked continuity on ECU plugs for Air Bypass valve and it shows .6. Also can tell the heater is working through touch and visual inspection of flap. Checked voltage at the plug and it is over 12. Just an FYI, this is a new professional rebuild. I checked valve lash and they are all at .08 intake and .10 exhaust cold. One of the intake is at .07 and 1 of the exhaust is .11, but I couldn't get the locking nut to release without the bottom nut moving as well so I left them where they are since my Engine builder said he would do the final adjustment after it is running in the car. Isky Cam 718149 http://iskycams.com/shop/index.php?main_page=product_info&cPath=127&products_id=960&zenid=52643cca0f4c18f0d1f5bc90bb2c6b9e .030 flat top pistons N42 head

Update: I tested it and it seemed to work, but the audible click was kind of soft so I replaced the Ignition Relay with two 4 pin relays to replicate the wiring in the FSM. Resulted in no change. Car starts and runs, but still no gauges other than volt meter which I had before. also still no turn signal activity which is what the FSM suggests to check in order to see if the Ignition relay is bad. In theory the water temp gauge may work, but I haven't run it long enough to tell since this is a new engine rebuild and I want to break the cam in correctly and want to make sure I have enough oil pressure to do that. Decided to remove the variable of the dash from the 1976 Z and put the original 1978 dash back in. Still no change. I'm stumped at this point what to test next in order to track down what's going on. Something that caught my eye as I was swapping the dash is that there are a couple single flat spade connectors for the multifunction switch on the steering column that do not plug into the same color wires. coming out of the MFS (actually the back of the ignition cylinder itself) they are both blue with red line, but what they plug into is a solid black and solid red. When we took this apart originally, I labeled every wire so I put the correct labels back together. Do you know if this is normal for the steering column wires? I also have no dash lights, but it sounds like that is likely a different issue so I'll do some separate research on how to resolve that unless you have any suggestions. (I've discovered that my dome light fuse keeps popping so I have a short there. As far as I can tell when I traced the wire in the '76 parts car that fuse blue wire with white stripe, only goes to the dome light and the engine inspection light. I don't see any fuse in the fuse diagram that indicates dash lights so I'm not sure what the cause there may be.) We tested continuity on the wire from the rheostat to the firewall plug and it is fine.

@Zed Head Finally figured it out after 3 days of continuity testing. The new relay EFI relay I bought was bad. Was able to figure out how to test it on page EF-33 and identified the problem. Thankfully the guy on ebay that sells it warrantied it as well and sent me another. Now I'm dealing with water, fuel gauge and oil pressure gauge aren't working. As I read through the FSM, it appears that these are symptoms of the Ignition Relay being bad, but for the life of me I can't find anywhere in the FSM instructions on how to test it. Only thing I can find is the suggestion on BE 43 to test the Ignition relay is check turn signals. Any other suggestions on how to test it?

Hi Steve, I know this is a very old post, but do you happen to have instructions on how to test the Ignition Relay? I've been able to find directions in the FSM on how to test just about every relay but that one. Thanks,

Thanks for the thought on the Fuse Link. I forgot to mention that I tested those. They are all new and I have power at both sides. Something else I forgot to mention is that the plug going into the EFI Control relay are all hot across the top and when the ignition is on and/or the engine is turning over the 73 plug is hot, but the other two are not.

Hi All, I'm brand new to this club/forum, but have found a lot of value in it over the last few months. My dad, son and I started a project car a few months ago. It is a car we bought from a kid who took it apart and couldn't figure out how to put it back together. I think we're 99% of the way getting it back together and running, but we're struggling with an EFI issue. This is a very long post, but hopefully that helps rule out some of the initial suggestions guys have and drill into the real issue quick. Just to answer the standard questions: We have fuel to the rail and can hear the fuel pump running. We have verified spark. We have tested pin 1 on the ECU connector and verified there is a pulse coming from the coil. While turning over, there is no motion of the tach. (Not sure if that is normal prior to engine start or an indicator of an issue.) When we spray a little carb cleaner into the air intake, the car tries to run for a second and then dies. When I tested the injector connectors with a standard test light connected to ground there is no signal/light. I tried with a Noid light as well and no signal/light while in run position on ignition or while turning over. We did the checks for "Engine will not start" on page 22 of the FSM EF section. The only one that didn't pass continuity was 1-(5), Water Temp Sensor. The others were all at .000 except for AFM which showed the following results: 6-8 = .182 7-8 = .194 8-9 = .102 I'm ordering a new Water Temp Sensor, but I have a hard time believing that would keep the injectors from getting a signal. I have already replaced the EFI Main Control Relay with a NOS I found. The original one burned out the Fuse Link wire instantly when we connected power. When I connected the new one (Part number 2523079903 in exchange for the original 2523089970, All of the exchange part numbers I could find said that was the correct one.) What I'm stumped on is when we did the checks on page 25 "Continuity check using Voltmeter" Check 2-(1) and 2-(2) were fine but every check under 2-(3) failed. So zero results on cylinder 1-6. Any suggestions on what might be causing this? A few forum threads have mentioned the wiring to the alternator could be an issue or possible the oil pressure sensor or wiring could be an issue. It sounds like the Fuel Pump Control relay relies on these. I'd like to check both of those, but I'm struggling finding the proper test procedure for those in the FSM. (and to be honest, am not sure I need to because the fuel pump is running, but I'll try anything at this point.) Any suggestions where I can find those tests in the FSM? I'm going to replace the oil pressure sensor just to make sure. I took the alternator in and it is charging, but maybe it isn’t communicating with things correctly even though it is charging? I didn't check the fuel pump relay or fuel pump control relay because I can hear it running and we have pressure to the rail. That's next on my list tomorrow though because I can't tell from the wiring diagram on page 24 if where pin 73 on the EFI relay goes to the fuel pump control relay pins 95 & 97 could be keeping the EFI relay from sending a signal to the Drop Resistor and main harness to send power and signal to cylinders 1-6. A couple other things we've done: We did an ohm check on the drop resistors as directed in page 34 and it came back fine. We did a ohm check on the line between pins 43/1 &43/2 on the Drop Resistor and pin 43 <73 edit> on the EFI main relay and it came back fine. But when we checked for voltage on the drop resistor side of that line there was no signal. Not sure if that is normal though with the Drop Resistor disconnected. <Edit, As I was looking at the diagram, I may not have put the correct number in the sentence above. I thought I tested the 43 pin on the plug for continuity to 43/1 &43/2 on the Drop Resistor, but I believe I actually tested 73. Sometimes it's hard to tell which pin in the FSM I'm testing. If you look at the plug, with the green wire on top middle, I tested continuity from the bottom right plug to 43/1 &43/2 on the Drop Resistor. I need to verify this tomorrow because I don't see how continuity could happen the way I'm remembering testing the plugs in my mind.> Not sure it matters, but figured I’d notify just in case. This car is a ’78, but the dash came out of a ’76. The kid had damaged the dash so bad I used a mostly assembled dash from the ‘76. Someone on another forum thread mentioned the tach could be causing an issue for another guy’s EFI problems, but he was getting power to his injector connectors, so I’m less convinced that is an issue for me. Thanks for any help