Help on injectors

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Help on injectors

Postby Danevansgolf » Thu 20.10.2016, 15:06

My injectors are doing weird things. They seem to be spiking twice and too early. I thought the injectors weren't meant to discharge at around 2milli seconds but mine are spiking at 1 & 2 milliseconds. If this is how they are meant to be well that's fine, but I have a feeling it's wrong, please someone shed some light on this info. I think it is something to do with bad earthing, but haven't been able to solve it.
Things checked so far is.
Injectors all work and tested
New cool packs
Mat sensor new
Map sensor bench tested and worked
Fuel pressure checked and works well.
Spark plugs are excellent
Ht leads are 2 years old. As there is a great spark on plug I presume they are fine
About to check the waste gate????

Can anyone think of anything else to check.
Hopefully I've put a pic on of my injectors showing this weird thing. It's not on elan scan but on a pico machine
Obviously on the diagram the left side is the voltage and the bottom is in milliseconds.

If anyone can check or knows what the injectors should be doing, then please also let me know.
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Re: Help on injectors

Postby Brit-Car-Nut » Thu 20.10.2016, 15:53

Have you checked the ECM to make sure nobody has installed a performance chip?

The injector utilizes a twin pulse design referred to as Peak and Hold. The ECM sends a high current pulse to quickly open it and then a lower current pulse to keep it open for the duration necessary.

You have a lot of posts, but noting I could find in logical order. Any chance of starting at the beginning and explaining what is going on in one post?

Since Lotus didn't follow the exact OBD1 spec, testing without software that understands the exact nature of the system will be nothing but confusing.

There are numerous owners in Scotland (Sorry, I obviously don't know UK geography I guess I should have said Wales?) that have ElanScan readers. Maybe someone will be willing to invite you over and make a couple of scans that you can then post here so one of the GURUs can try to find any anomalies in the report.

You said you bench tested the MAP sensor. How did you do that? Where did you get the specifications? I have been struggling with MAP questions since 98% of those I look at turn out to NOT be the correct 2 BAR version we need.

Identifying and testing GM MAP Sensors.pdf

Most of the sensors the ECM uses to figure out how to fuel the engine look and fit like all the other GM sensors but they rarely interchange. It is critical that you test all of them which is a nightmare but ElanScan does that for you, so you can see the reported temperatures and pressures that the ECM is using to calculate the fuel flow. A failed or out of spec sensor will show up in the reports.

I STRONGLY suggest testing with ElanScan or a service center that has the original GM/LOTUS TECH1 with the correct M100 cartridge.

The Electrical Manual lists ALL of the grounding points. Go to each one and unbolt/disconnect each one, clean the connections and coat with di-electric grease and reassemble. That permanently eliminates the worry of a bad grounding/earth connection.

Best of luck. I hope you figure i out.
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Re: Help on injectors

Postby GeoffSmith » Thu 20.10.2016, 22:01

Dan, those traces look fine to me assuming you are measuring the drive voltage to the injector. At the trigger point (t=0), the voltage is dropped to 0V to ramp up the injector drive current as quickly as possible where it reaches a peak at t~1ms. The drive voltage is then modulated to reduce the current, causing inductive kickback and voltage overshoot. The hold current is then stopped at t~2ms where there is another inductive overshoot.
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Re: Help on injectors

Postby Jeemy » Sat 22.10.2016, 15:58

Hi Dan,

I don't think you are in Scotland unless you've moved but in case you have, I have Elan Scan and a lot of other diagnostic equipment here in East Lothian. You are more than welcome to bring the car down to the workshop to look at it together,

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Re: Help on injectors

Postby Danevansgolf » Mon 31.10.2016, 16:25

quick update..
firstly i have had the elanscan plugged in and have pulled a ton of data off the car at various speeds and gears etc..can i email somebody with the data files, for somebody to look over them please?????

secondly you wanted to know what is going on.
hmmm where to start..

car has always had a starting issue.
cold start, starts on the button everytime
warm/hot start, takes at least 5 seconds for the car to fire up, once fired up runs fine.

NEW Problem.
Recently i took the injectors out and sent them away to be ultra sonic cleaned, came back and refitted them, ended up taking the cam cover off, as i couldnt re sit them correctly...
After that, the car wouldnt run correclty.. ie when you put the throttle down hard the car retards itelf and doesnt want to give me all the power, ease off the throttle and the car runs perfect, again full throttle hard and again car bunny hops and retards itself..??????????? any ideas.So genlte thottle car is fine, hard throttle car hops and jerks itself?
ill list all engine parts ive changed, but bear in mind the car has run ab fine, only since changing the injectors has the car developed this problem. I also had the air hose and cleaning nozzle around the back of the engine to blow any leaves and crud away? Could this have done something..??HMMM.
right in no particular order.
1.mountain chip v4.5 3/4 years ago
2. power steering pump 2 years ago
3. temparature gauge sensor 2 years ago
4. HT leads and spark plugs 2 years ago
5. Thermostat 2 years ago
6. cam angle sensor 1 year ago
7.fuel filter, last year,
8. cam belt,water pump, 8 months ago
9.coils and board behind, last month
10. Manifold air sensor last month

i HaveThought about changing the fuel filter only because when changing the injectors you need to drain the fuel out of the lines, so i may have pulled alot of s**t/crud from the tank?
Im clutching at straws here.. my diagnosis mechanic has given up, hes emailed me a load of data files

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Re: Help on injectors

Postby Simon_P » Mon 31.10.2016, 21:55

Danevansgolf wrote:Im clutching at straws here..
Yes, and clutching at straws is rarely effective.

It is only a car!

You have changed several things so do the following correctly, methodically and in order. Even if you think you have already done them.

1 disconnect the battery to reset the ecu
2 check/set base timing ( in service mode)
3 set idle " "

Go for a drive
If that doesn't fix it
4 check HT leads plugs connections etc
5 check hose connections
6 check vacuum connections
7 check electrical connections
Go for a drive

From cold ie the next day
Connect elanscan.
Without revving the engine or driving anywhere
Start scan, start engine, and let it idle until the fans come on. Then post the scan here.

The total cost of that is zero!
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